As someone who's never really understood why gambling is fun for people, this doesn't surprise me. Given that enough people seem to find it exciting enough to spend money for nothing other than a less than even chance to win back more for it to be its own form of entertainment, it makes sense to me that maybe quite a lot of people are predisposed to gambling addiction, and the reasons it wasn't not common before were social (easy access, potential social stigma due to a lack of anonymity, etc.). The fact that these obstacles have all gone away so quickly also leaves people entirely self-reliant on making sure they don't overindulge, similar to how binge drinking in college (in the US at least) is fairly common because of how much easier it is for most students to access alcohol when living at school compared to at home. Addiction is a medical condition after all, and while sports gambling might be the catalyst for the rise in gambling addiction, I suspect that the underlying susceptibility for it has always been there for a large number of people, and they've just been lucky enough not to be exposed to circumstances where it becomes addicting enough for it to be an issue in the past.

Lol and water makes things wet