However, you could also argue that it's the equivalent of buying a pack of Pokémon cards, baseball cards, etc. - which are not regulated.
My intuition tells me that given the addictiveness and how this disproportionately affects the most vulnerable members of society, the practice should be regulated much more tightly. Also, given that these are digital goods, a more relaxed "return" policy shouldn't harm any company that is offering in-app purchases in a good-faith / non-exploitative manner.