I still got enough robux to DevEx just from premium roblox subscribers playing the game. (If I cash it out i would get a few hundred dollars. Which is nothing for me today but absolutely a lot of money for an aspiring teenage developer.)
If we are talking about game mechanics, they get copied all the time, of course. If it's about superficially reproducing a game including the assets, I don't think any big players on PC or consoles steal ideas from indie/smaller developers. That is despised and likely not allowed by the platform, if not challenged in court.
(I have no idea about what happens on mobile platforms)
edit: looked at the old stats online. a few years back that game was pulling $1,500+ with no effort each month