I look at it like this, firstly sometimes there are cool pre-order exclusives that you wouldn't otherwise get when buying at launch. Sometimes pre-ordering is also cheaper (common especially with early access type schemes), and really it's riskless for the scrupulous buyer. If you feel like the game let you down, you can refund it. By pre-ordering and subsequently refunding, the trash studio sees that money enter their pocket and is then taken away from them again. It's a measurable metric to base success or failure off of. If you just don't buy a game because you waited until launch and found out the game was shit, they have no idea they lost a potential customer.