It's not always gambling. There are also collectors and people who just like to show off. Also, the usually f*ing rich dude who has no understanding on the difference between $2 and $20k. Games today are the new social club, where you go and meet and show off your life. And as there are corners for the average people, there are also corners for the rich and powerful. There are some games which really just exist so rich dudes can casually meet and show off how much money they spend on some stupid skin. Similar, some other games have pay2win, because enough rich people live by the philosophy that money can buy you anything, including an easy win.

The gambling-games are only the most obvious whale-traps, and they usually not even aim for the filthy rich, but the middle class rich. The rich rich-games are less obvious, because the casuals are not rich enough to even get high enough in that game to gain access to the juicy parts.