This is a really famous case and is fairly Kafkaesque.
It comes down to this:
> In 1992, a French court ruled that having entered the country legally, he could not be expelled from the airport, but it could not grant him permission to enter France.
He was legally stuck at the airport with no options from 1988 to 1995 when Belgium said they would take him. After that he stayed due to stubbornness in refusing to sign bureaucratic papers that did not represent his mental truth, which was affected by the years trapped and made him a bit off in the head like it would anyone. So he remained stuck.
He never could afford to stay at the airport. He was trapped there by bureaucrats. Humanists recognizing his dilemma gave him food.