Thirty years ago, a pioneering journey across Asia blazed a trail for millions of budget travellers. The planet doesn't seem so lonely these days

Twenty-odd years ago, the American Richard Evanson made his fortune from cable TV, and cashed in his chips. Today's equivalent would have been making millions and getting out before the bust. He then, almost by accident, bought an island in the beautiful Fijian Yasawa group and turned it into a resort. A very small (just 14 rooms) and very expensive (a straightforward £1,000 a night) resort. The 14 rooms ties up very neatly with Turtle Island's sum total of beaches – 14. Which means you don't have to share your stretch of sand with anyone – apart from the person who's sharing your room. There are also about 15 staff for every guest. But there is one catch. There's a minimum stay of seven nights. So count on £7,000 as the starting price for your stay.

Turtle Island is not, as you might have guessed, a backpacker resort, but I was not there as a pampered guest. Last month I travelled to the island because Richard Evanson was getting into the backpacker business.

Backpackers are like the poor. They've always been with us. I was reminded of this just the other day when my mobile phone rang and my daughter announced from Bali in Indonesia, that her boyfriend had a bad case of Bali Belly and asked if I had any advice? She, and her boyfriend, are backpackers. I was a backpacker back in the Asian hippy trail days and I certainly met plenty of backpackers when I lived in London, way back in 1971. Friends of Australian friends regularly turned up to claim a patch of our flat's floor.

But just who are backpackers? Definitions tend to be fuzzy. Of course, they're generally young. Sure, there are oldies staying in youth hostels, travelling on beaten-up buses in South America or scouring the ads to buy old cars to drive around Australia, but in general backpackers are youthful. Simply being young, however, is clearly not enough. When a rich American family stays in the Savoy, does the teenage son qualify as a backpacker just because he's the same age as the Canadian kid staying at the Rotherhithe youth hostel? Of course not, although if he ventures out on his own that evening and bumps into the Canadian in a backpacker pub, perhaps he's a backpacker for the next few pints.

Some people define backpackers by where they stay. In Australia, where the backpacker business is so important that PhD theses have been written on the subject, the Bureau of Tourism Research defined them until recently as anybody who stayed a night in a place calling itself a backpackers' hostel. So 300 doctors at a convention in Sydney who venture into the Outback and stay a night at a backpackers' lodge along the way could suddenly transform into 300 more backpackers.

"We're 'Hilton Hippies'," an older couple explained to me once. They were happy to travel without reservations, by public transport, without a definite route, with a flexible schedule, but at the end of the day they wanted a hotel where the shower ran hot, the air-con ran cold and CNN was on the TV. Were they backpackers? Yes on some counts, but if the style of accommodation is the litmus test, then clearly not on others.

Engaging in holiday work is another backpacker identifier. Sometimes it seems half the pubs in London would shut down without visiting Aussies and Kiwis, and no fruit would get picked in Australia without gap-year Brits. I once did a circuit of the backpacker establishments in San Francisco and the reception greeting at every single one of them was in a distinctly Irish accent. Being a vacation worker should be another backpacker test – but what about the temping Sydney lawyer in London, or the Scots accountant making big bucks in Melbourne. Are they backpackers?

In fact, all these elements have to come together to create the backpacker experience. Just having cheap accommodation is not going to do the job if there's no way of getting there. And even if you can get there and there's somewhere cheap to stay, backpackers are not going to stay if there's no reason to do so. Without travel they can't get there, without things to do they won't stay, and if any one of those vital elements is missing the whole picture can fall on its face.

Jump-on, jump-off bus services have been a prime force in making some destinations backpacker friendly; the Scottish Highlands for example. In Australia, the scenic Great Ocean Road route from Melbourne to Adelaide offered plenty of attractions – from the Bell's Beach surfing Mecca to the historic sites of the Shipwreck Coast – but the hostels along the coast stayed unhappily empty until a local entrepreneur invented a company known as the Wayward Bus.

A growing proportion of its customers are young Japanese, perhaps the fastest-growing contingent of backpackers. Unlike their parents, they don't all need to follow a small flag on a pole. See a cyclist pedalling across the Nullarbor desert in Australia and chances are they'll be Japanese. I came upon an Outback road sign once, completely covered on its reverse side with tales of Japanese motorcycle derring-do.

Even as a destination, expensive Japan has joined the backpacker circuit, with lots of hostels, lots of work and a surprising amount of adventure travel opportunities.

One day even Americans will get longer vacations and decide a hole in their resumé is not necessarily a sign of decadence. Wider horizons and more adventurous travel instincts has been one of the worthwhile side effects of the dot com boom and bust in America.

So why should we love backpackers – whether "we" are a country trying to attract visitors, an adventure travel operator trying to attract participants, an airline, train or bus company wanting to put bums on seats, or even a guidebook publisher wanting to sell books? Backpackers are just one group out of many – if they're only 10 per cent of the whole travel market, why should they deserve special consideration?

Look at Coca-Cola – often cited as the world's number one brand. It's been around for over a century, the drink is the same, even the bottle is the same, but Coke is never promoted as a drink for pensioners. Nobody says, "You drank Coke 50 years ago and you'll still enjoy it now you're 70." No, Coca-Cola continuously reinvents itself. It's the same with travel. Forget about catering for 70-year-olds – the people you want to sell travel to today are the people who are going to be going places for the next 50 years; the backpackers.

So why was Richard Evanson on Turtle Island helping set up more backpacker resorts in Fiji's Yasawa Islands? Well, it could have been because he wanted to keep on side with his local neighbours. After all, one village did try to take over his fancy resort after the Fijian coup last year. It could have been, as he claims, pure altruism; he's certainly been closing down his own resort once a year and putting on a medical camp for the islanders, aided by volunteer surgeons, doctors and dentists, many of them past guests at Turtle Island. It could be an easy way of keeping mega-resorts at bay – better a nice low-key backpacker establishment on the next island than some monster package place. Or it could be the simple realisation that today's backpackers are going to be tomorrow's big spenders.

Let's face it: if a 19-year-old can get it together to get herself to the other side of the world to live on £10 a night on a tropical beach, she may well be back in 20 or 30 years to spend £1,000 a night. Backpackers have all sorts of desirable qualities.

They're pioneers, going boldly where no tourist has gone before and pointing the way, today, to the popular destinations of tomorrow. They're tough, too: when most sectors of the Fijian tourist business stopped dead after the coup in Fiji last year the backpackers kept coming.

The money they spend is "sticky": it stays with the local people, and it doesn't leak out to international investors and tour operators. They're adventure- and activity-oriented: having spent their money to get there they don't just lie on the beach – they'll go and do things. Plus today's economy-minded backpackers are very likely to be tomorrow's bigger spenders. There's lots of them. They go lots of places. And we should love them.

Tony Wheeler is co-founder, with Dr Maureen Wheeler, of Lonely Planet travel guides