Con the coach into thinking they're the next best thing since sliced bread, so the guy will let them train for free.
Most places have an arrangement where pros don't pay monthly fees, the exchange is they give them 10% of the fight money, which is peanuts for anyone that's not a big draw. Pros I know make around a 600:800 arrangement. The most was a lucky one that managed to get 1200:2000.
The whole idea of combat sports as the savior for income was because in the old days, alot of boxers were absolute crap in society. The fact that boxing to them was a better career change is testament to how down they were.
But to the point, I really don't think anyone doesn't work. A close friend (high ranked ammy) didn't work for awhile, because he saved as much as he can when off camp, has a real generous friend that let him stay at his place for free. Lives a very minimal lifestyle, then when in camp quits work. I think on average he works about 4 months of a year of total accumulated time.
His case isn't as common these days, most of the time they'd have to work regardless. Hell everyone does