Hobby dev here with some insight into this.
The talk about wealthy people who don't care and people with serious addictions and mental health issues only covers the top few percent of whales - But a lot of the top whales, and a huge percentage of the whales in general, consistently fall into an interesting pattern. They're not gambling addicts, and they're not rich. Rather, they are overwhelmingly "Failures to Launch". These people generally have some careers or skills, but are either stuck in dead ends, stuck in entry level, or derive no pleasure or satisfaction from their work. Think generic middle manager type stuff, but overseeing a team nobody gives a shit about. They tend to have no real financial obligations or future, no family, few to no friends, no hobbies or passions, etc. They are the stereotypical failure bugman sitting on his couch in his apartment with no thoughts going through his head. They don't have relationships, they don't have any goals to save for to the future, they're just going through the motions.
These people eventually find these sort of games, and if they start spending, something happens that has quite likely never really happened in their lives before. They're succeeding. They don't really care about the money or the fun-value comparison to other things, because that doesn't matter. Suddenly they're seeing success, they're getting things. They're likely experiencing their first social outreach in years, with clans always hunting around for whales to buff their ranks (Seriously, social mechanics in whale hunting games are overwhelmingly designed to encourage and drive this behavior). Their clan mates actually seem to care about and be interested in them, and often overlook awful social flaws and awkwardness because they're pulling everyone else up the boards in events.
These people tend to hang around until one of a few things happens. Sometimes, a failure to launch actually goes off. They manage to start dating, or their career shifts and there's actually something for them to work towards. Sometimes clanmates introduce whales to other hobbies, and they stop whaling to pursue those instead. Or, they whale too hard, and financially crash themselves out of it. They're aware of the money they're spending the whole time, but they push forward until they break. Not out of gambling addiction, they're not chasing a shiny for the thrill, or obsession with the thing in question. They're chasing the validation others give them for having the numbers.
Gacha's aren't special in having these people latch to them though - Failures to Launch tend to glue themselves to the very first thing that gives them that satisfaction, which is where you'll see the weird guy who's still obsessed with Yugioh or something in his thirties. Gaming in general has a LOT of them due to the whole dopamine factory design. Gacha is just uniquely positioned to allow failures with even less skill that call of duty casuals to excel as long as they'll pay.
