My kids have started playing Roblox recently and they have started asking for some Robux so they can buy crap... I really don't get how so many people are into spending dollars on this stuff. Everything they wanted was ~$10-20 NZD and it was just throw away stuff, like a costume, etc. And then it's only useful in that one game you have brought it for. It blows my mind that it ever got this popular.
My niece was about $1500 into that game before anyone realized what she was doing. She had been asking for gift cards and what not to get the credits. My sister realized what was going on when she added it all up. She thought it was a harmless game her kid was playing. It has a lot of dark patterns designed to scrape cash. There is nothing more expensive than a 'free to play' game.
Addiction triggers and reward center abuse. This, to me, is no different than bright slot machines.