Re: The whole thing
>>"Because you don't understand how people can spend money on a hobby that boggles anyone who doesn't engage in that hobby?"
That's not what the OP said nor what they were getting at. Playing a game - understandable for a variety of reasons, surprise, challenge, humour, story, whatever. Paying money to do so, therefore likewise understandable. What was questioned was where someone pays real money for achievements. You can earn coins or equipment etc. in game but many games will also let you buy those things with real world currencies. That short-circuits the entire process and is basically just a way to fire the synapse in your brain that says "achievement".
Such a game model (often the game itself is free) is basically providing the minimum necessary to define success for the player (I've got X weapon, I own 20 pigs, etc.) and then getting people to pay money to get that success without doing the necessary playing / developing the relevant skill level.
And THAT is what is wrong with it. If the achievement is detached from any entertainment the game itself delivers in getting it, then it is utterly arbitrary. You're paying someone real money to have a message on screen saying "you have 20 pigs". Or again, whatever you collect in that game.
If a purchasable extra to a game delivers additional "game", like a DLC expansion pack for a role-playing game, then that makes sense - it's essentially gradiating the price of the game according to how much you play. But paying to avoid having to play - that's deeply flawed and basically just manipulation of the brain's reward modelling.