Sounds like the issue is that he doesn't have any realistic plan and he is gambling over his budget.
Fear is a normal feeling that can happen when we bet more then we want to lose. $15 can be peanuts to someone, and too much to afford for someone else depending where they live, how much they make and what are their life expenses. And if someone is actually afraid of losing that $15, that means it's a lot of necessary money for them.
Why is he gambling in the first place you ask? To me this sounds pretty normal. Not all people have a plan and they play like they feel like at the moment. He listened how he felt and felt that fear. If he could combine this self awareness to some plan, he probably would do ok.
He expressed his feelings but his permission here may not be what we see. He did not bet his entire $15 at once because if he lost the bet he would have lost the entire $15 so he may have bet the $15 in small amounts. He may have planned it that way but I do not know what he wanted to do exactly.
The mindset for betting actually depends on the time. So it seems natural to me that he would have bet the $15 in several ways instead of betting it all at once.
Most folks do go all out in gambling when they are frustrated most times , due to some certain losses and the mindset of always trying to get back their losses back by gambling or staking huge amounts of money that’s why gambling is not for the weak as folks usually say because if you don’t have good self control you only messed yourself up .