I've probably spent tens of thousands of dollars across multiple games and other places (like paperdoll websites that have gachas) and I will likely continue to do so in the future.
I'm not even wealthy, I work a part time job and pay my own bills, but I usually have an entertainment budget of $60-$150/mo that I set aside, and I'll typically blow that on mobile games or other gachas.
Is it exploitative? most certainly, and I'm fully aware that I'm nothing but a minor piggy bank to the publishers and developers, but I'll continue to pay for these services going forward until they're removed or regulated because of one aspect that I never really see addressed when it comes to gacha and similar things: the social aspect.
When you see everyone that has the Newest & Best shiny thing, and then you're stuck there wearing the old thing, you want to buy the Newest & Best too. It's not even exclusive to gachas and lootboxes, really -- it's part of being human, keeping up with the Joneses, but given then random nature it becomes particularly vicious, because when all of your friends have those cool new items or skins but you're still stuck wearing the old boring items from last month, you're tempted to go over budget and spend even more until you get it.
I've done it with Overwatch as well -- I spent $200+ a few months into the game, because I wanted to have new skins to show off to everyone else. I wanted that false sense of superiority that often comes with cosmetic items, and having myself and a few friends all wear those skins while the "plebs" were wearing default skins was a rush, which you end up chasing during every new event if you aren't lucky enough to unlock the skins for your characters immediately.
It is 100% predatory and I won't sit here and defend it, although it's incredibly hypocritical of me because while I'll naysay it, I continue to support these practices with my money through sheer desire to stay fashionable, or to gain whatever edge I can over others.
Heck, I even spent $100 on ME:A MP because everyone was talking about how good specific classes and weapons were, and I wanted to be one of the elite players with those good items, so I dropped cash until I got them.
It's worth keeping in mind though, addiction and gambling problems are a key source of worry for these issues, but we can't take these things in a vaccuum and have to consider other potential influences and peer pressure into buying and engaging in this behavior which lets us be preyed upon, which makes even cosmetic only boxes very harmful.