Before Joe Calzaghe and Roy Jones Jr share their millions this weekend in Manhattan, here is a timely and painful reminder of how fast they could lose them. It comes from over the Harlem River in the South Bronx, where, in the Patterson Projects, a public housing programme, we find Iran “The Blade” Barkley, who won three world titles and twice beat Thomas Hearns.

It is not the loveliest part of town, the kind of place you would go only with a famous prizefighter for support. Outside his block of flats lie flowers and candles, a shrine to a 20-year-old shot and killed by his best friend in a dispute last Friday. This block is less than 100 yards from the one in which Barkley grew up. Between one and the other, he managed to spill $5 million (about £3.14 million).

Actually, he thinks it is $5 million but he has no precise figure. He has no exact sense of accountability for where it went, either. He certainly has not a dime more than when he started. And he started with nothing.

So it may not come as a surprise to hear that, at the age of 48, nine years retired and palpably unfit, he plans a comeback. He needs it financially. He also needs to have the scar tissue that hangs heavily over his left eye removed and was consulting his doctor on that very subject on Tuesday. Only then will he stand the slimmest of chances of exhibiting sufficient fitness to get his licence back.

Here is what life is like without the licence: in 2006, he took a bout, unsanctioned, in Aruba against a twentysomething amateur whose name he cannot recall. He took home a purse of $7,000, most of which went on child support debts, although the real price of the bout may be that he used it as an indicator: if I do well, I know I am good enough to return to the sport. And he won.

Thus, last year, he accepted another unlicensed fight in a Native American reservation in Idaho. For this contest, he swears, he still has not been paid. He also claims that he was “kind of kidnapped” because he tried to walk out on the promotion but, as he had no money for a cab, was forced to stay.

The haplessness of Barkley's downward spiral would appear to have no end. For blame we could look to the sport's infamous inability to look after its own, to his lack of education, to his belligerent refusal to sign up to employment outside the game or to the breathtaking illusion that he genuinely has a future in it, any of which have been the downfall of the battalion of boxers washed up before him. But this is truly one case where you wish someone could step in and catch him before he falls any farther.

Are you training hard for the comeback, we asked. “Yes,” he replied enthusiastically until put on the spot by his sister, with whom he shares the flat, when he changed his tune. “I've not got time to train. I don't run, I don't do nothing.”

And to the question, “How good do you really think you could be?” he smiles and delivers the stock response: “Better than ever.” Outside his block is a mural, painted by a friend after the first Hearns bout, but so faded now that it is curiously symbolic. The neighbourhood still knows him, still hails him as “Champ”, and some still recall his triumphant return from Las Vegas post-Hearns, in 1988, when a banner was strung up for him and he paid for donkey rides for the local kids. “This neighbourhood is like a trap,” he said. But that Hearns bout in 1988 should have been his exit. His income until then had been largely what he reaped as leader of a Bronx gang called the Black Spades. What did they do? “Pretty much everything that was wrong,” he said, with no specifics bar “sticking guys up and running banks”.

But that Hearns contest was the start of a lucrative run. It delivered a pay day against Roberto Duran in the bout of the year, one in which defeat only enhanced his reputation, yet after further losses to Michael Nunn and Nigel Benn, he was still considered sufficient box-office quality to go in against Hearns a second time and finally reap the pay-day of his dreams, $1 million for the last big contest of his career, against James Toney.

So where did the $5 million go? Some of it he hid in his apartment; he did not trust banks. Sugar Ray Leonard and Marvin Hagler, he said, had good financial advisers but he learnt about money “from the guys in the street and some of them were drug dealers”. “When you're young, you don't know how to manage your money. You spend it, you start buying cars, hanging with friends, partying, thinking that you've got enough,” he said. “I also helped people. Their husbands went to jail and I'd pay the rent. That was my blessing. I was the angel for everybody else. I had everything: a Lexus, a Mercedes. I had an apartment in New Jersey.”

Indeed, he also bought a tenement building in the Bronx and a car wash in Yonkers, but could not afford any of them outright and the struggle to make the payments was not helped by an appetite for gambling in Vegas and two divorces, plus the child support required.

“For the second Tommy fight, I think I only got half a million dollars,” he said. “Then you pay your trainer, pay your manager, then Uncle Sam [the taxman] comes in at the end. I had nothing to give him. That's when I started trying to catch up.”

He never did catch up. And he is too proud and delusional to divert his gaze from the ring. “Two or three months' notice and one tune-up fight is all I'd want,” he said. “Give me anybody after that.”

Where does the safety net lie? To a limited extent, in the hands of Gerry Cooney, the former heavyweight who has set up the Fighters' Initiative for Support and Training, which aims to pick up struggling souls such as Barkley, retrain them and refocus them on life after the ring.

Cooney, however, says that he has tried with Barkley and failed. Barkley, he said, does not want a standard job. And Barkley does not disagree. He worked in a Bronx school last summer, training local boys to box. “But I wasn't earning enough,” he said. So he walked away.

His problem, though, is that he no longer has a destination. When he makes his comeback, he says, he will have his mural in the Bronx touched up along with a list of his titles and achievements in the ring. The sadness is that he cannot see how far they have faded.