The games market is large, but not infinite. Like, there may be many space games, but only one space sim that has the depth and complexity of KSP 1, and that’s KSP 1. Not to mention that a lot of gamers have no idea what engine their favorite games use. For instance, I was shocked to discover that Disco Elysium used Unity because it looks so different from the “stock Unity look”.

>Not to mention that a lot of gamers have no idea what engine their favorite games use.

If you start to boycott something, you typically have done some research (why else would you have wanted to boycott it in the first place). I.e boycotting Nestle means that you research where the company may have their fingers in and avoid that.