I was recently at a lan party for a friend's 40th birthday (something I don't think any of us had done since highschool or so!), most of them are way more into gaming than me and have been consistently since childhood. I was pretty shocked at one point when they went on a loot box binge and I witnessed them drop hundreds on loot boxes etc (I don't know what it's called, the keys or whatever). Definitely didn't seem like the first time. These are adults with children of their own. There is a demographic out there of people I wasn't aware of, not necessarily whales, that have a ton of disposable income for this fluff. And valve has their hooks in them for whatever reason.
I’ve watched grown adults with kids spend hundreds on baseball tickets and beer in one sitting, too. I’m not trying to invalidate your point. But also be careful about making value judgements (“valve has their hooks in them” reads as a negative sentiment to me). People spend money on entertainment and there are worse vices out there.
Grown adults blowing a couple hundred on some fun doesn't really seem that crazy to me. How is that much different than going out to the bar, sticking a benjamin in a slot machine, or buying some collectables?