He’s only 28, but Steven Bartlett is set to breathe fire as the youngest ever dragon on the hit BBC1 series Dragons’ Den.

“I’ve loved the show since I was 12-years-old,” says the multi-millionaire entrepreneur, who as an 18-year-old applied with a business pitch, but was unsuccessful.

“Outside of the den we’re all friends. Inside the den, anyone who is competing for the same deal as me could potentially become an adversary,” he says of his fellow dragons.

Bartlett, who is currently filming the new series in Manchester but won’t be wearing a suit in the den, has followed an unconventional path to success – expelled from school, he dropped out of university after one lecture and lived penniless in Manchester until he found his feet in social media marketing.

At 21 he co-founded social media marketing agency Social Chain, which was valued at £200 million when he took it public and resigned as CEO at the age of 27.

Today, he lives above his offices in east London, so rarely switches off as he has his fingers in so many pies .

There are his multiple investments in health and mental health companies; his podcast, The Diary Of A CEO, in which the rich and famous open up to him; his book, Happy Sexy Millionaire, a memoir and guide to fulfilment, love and success, which has become a bestseller.

Born in Botswana, he was brought up in Plymouth, where his Nigerian mother, Esther, tried various business ventures, while his dad was a civil engineer.

The youngest of four children, Bartlett went to a secondary school of 1,500 pupils, but can only recall one other black child apart from his siblings.

“I was trying very hard to fit in. I started relaxing my hair to make it straight,” he remembers.

“I was trying to be Indie one second, listening to a certain type of music that I didn’t really enjoy that much, and the next minute would dress in Fred Perry and Rockport and Stone Island. I was also trying to be white, I guess.”

But there were racist insults, and he says: “Another time I got a kick off a kid who called me a black b******.”

At school his business acumen was noticed by staff and he showed his flair by organising events and trips and stocking vending machines. Eventually though, he was expelled while in the sixth form for poor attendance, banned from the sixth form prom and the celebratory school trip to a theme park, which he went to independently anyway.

When he left home at 18 and dropped out of university after one lecture, he ended up living in a partially boarded-up house in the worst part of Manchester, stealing food to feed himself.

But he soon picked himself up and launched a social media marketing business, later founding Social Chain with a pal – both ended up millionaires.

But he has found that ultimately money doesn’t buy happiness. “I thought I was unhappy because I didn’t have money – but I was just insecure,” he reflects.

That old adage so often comes from people who do have money, but Bartlett counters: “I feel the same now as I did when I was 18 and broke. It turns out I was happy then, but was under the impression that more stuff, more wealth, would scale my happiness further.

“I thought if you have one million, you are one million happy, if you have five million, you are five million happy. But what happened was that I was insecure.

“Yes, to a point, it makes you happier if you can buy nice food and afford to go to the gym and have a better lifestyle in terms of health, but beyond a certain point, once you’re able to stop the bailiff knocking on the door and feed yourself, there’s not much to be gained from money.”

There’s a telling point in the book where he recalls his elation at finding £13.40 in loose coins down the back of a seat in a takeaway when he was penniless, then fast forwards a few years when he’s in a five-star hotel and learns his company has been valued on the stock market at £200 million – and he feels nothing.

“It’s all relative to your situation,” he says now.” Finding that £13 was the difference between feeding myself and not feeding myself. But when you’re already doing fine, what difference is tens of millions going to make? All the things that meet your fundamental basic needs can be attained once you have, say, £40,000 a year.

“Yes, you can fly better or buy a super-nice car, which might give you a fleeting amount of pleasure, but not sustained happiness.”

One of his long-term goals is to have six children, although he is currently single.

As for the future, Dragons’ Den is a great gig, he agrees.

“It’s a dream media job for me,” he says. “I’m looking forward to bringing a new perspective and a representing a different world on the show, like the digital social media Web 3.0 tech world on the show, which I hope will make it resonate with a new, younger audience.”

He’s not worried that the show will give him a much higher public profile.

“I’ve had a little taste of it – I have two million followers online so I get stopped once or twice a day if I’m out and about. Dragons’ Den will be a different audience.

“I think a lot about the media and what people will say about me, but at the end of the day if I was going to succeed in achieving my potential, this was always going to be an unavoidable consequence.

“I’m not particularly bothered about what other people think of me, largely, and I’m not interested in fame, as in shallow, empty, attention. But I am interested in having attention that I can leverage for things that matter to me.”

Happy Sexy Millionaire by Steven Bartlett is published by Yellow Kite, price £14.99