This isn't uncommon in the slightest. Young men, too much time, too much money, little life experience, no ability to make long-term, wise decisions, and also attuned to trying to match the rush they get from footy.
Steve Price was one notable one that gambled away hundreds of thousands, if not millions early in his career.
I am sure it happens less with clubs being more proactive in education, mentors etc nowadays but clearly it does still happen. Managers should be more involved, as well. I remember reading that Benji's manager had full disclosure over all his bank accounts and demanded accountability on how his money was spent. Maybe that's an overreach, but it's certainly better than the worst case.