People with a gambling addiction will find an outlet for it unless they get help controlling it, just like people with any addiction. Addiction is treated on an individual basis, not by banning an activity that the vast majority of the population can partake in with self-control.

We don't have tons of public numbers to be able to discuss the initial development, licensing, marketing, support and ongoing development, distribution and overhead costs vs initial costs, expansion and MTX income of games at a large scale. But you can be sure the companies that make the games have those numbers, and they're used for pricing and budgeting of future development. And that's before we open the can of worms that is discussing how much profit is ethical.

Maybe they could make less money, maybe they could not make certain features, but where does the ethical line fall when it comes to predatory features and marketing? Who needs protection? From who? How do you implement it without infringing the rights of others? Is it ok to let them gamble if there's a deterministic worst-case scenario? What if there's a limit on how much they can spend? What if purchases are purely only deterministic, but they're limited time exclusives that will never return? What about if you can earn them by playing or pay extra to just get them up front or faster? What about if they carve that feature out of the main product and sell it as an additional cost? These are all predatory in some way, but we don't need to ban them all when a person can make their own value judgments and interact with games in a way that brings them enjoyment. Otherwise, it's a slippery slope to asking why we even let people "waste" money on entertainment.