To me, it sounds like Jeremy Lin thought he had another NBA contract coming, and it's hitting him hard that there were no offers. Personally, this is part of the reason why I feel a lot of athletes (and people in general) end up broke. Now this doesn't apply to Lin specifically, I heard he's frugal/smart with finances, but the situation he's in is what gets a lot of people in trouble.
You look around the league, and there's always several players pushing 40. From former superstars to career role players, and everything in between. I think it's easy for guys to fall into the trap of living lavishly now, but think they'll start saving with that next big contract. Only that next big contract never comes.
I bet Lin thought he had at least another $15m-$30m/2-3yr deal left in him, and couple of vet minimums after that.
We know Isaiah thought somebody was backing up the Brinks truck for him, was probably expecting a $100m contract, and probably thought he could play till at least 35 back when he was in Boston. Now after a couple of minimums, not even sure he'll be in the league next year.
Antoine was the same way. I know he thought he had another big contract left in him, only to find himself bouncing around the G-League trying to convince an NBA team he could still contribute.
I'm sure a lot of the guys think, "if a guy like Kyle Korver is still signing contracts to play when he's 39, I'm better than Korver, I can play at that age too if I want, so those contracts will be there." A few role players are able to sign decent contracts well into their 30's, so everybody thinks they'll be able to do it if they want.
So players are planning for that extra $20m, $30m, $40m+ in earnings that never comes. And regular people do this too, think they'll be able to work until 65-70 (if they want), only to be laid off at 45-50 and then can't find anybody to hire them anywhere near their previous earnings. It's a cold world.