Something that i haven't seen mentioned much is that some people just prefer to work on custom engines (i'm willing to bet that the main reason John Carmack mad

Something that i haven't seen mentioned much is that some people just prefer to work on custom engines (i'm willing to bet that the main reason John Carmack made his own engines was because he liked working on his own engines rather than the costs of licensing). I know of at least a case (i wasn't part of it myself) where after a developer decided to switch from their custom engine to Unreal, almost the entire engine team quit. FWIW personally when judging potential workplaces i bias towards those using custom engines since there is way more room for having an actual impact on the project and i am more likely to learn something new from a custom codebase than the 482th Unreal fork. The fact that people often feel the need to justify working (almost always in a defensive stance) with a custom engine shows that they simply prefer to work with a custom engine despite other concerns. Also there isn't really a clear cut distinction between AAA and smaller studios using custom and generic engines - while indies are more likely to use something like Unity, that is mainly because there are way more indies than big teams and many indies do not have the knowledge for a custom engine. But there have been many successful indie and small studio games with custom engines and AAA studios with licensed engines to say that if you're Rockstar go with custom, if you're small go with 3rd party engine. Honestly i think the people involved are way more important (and likely to affect the choice of an engine) than any budget or size concerns (i'm not even considering the game type as most custom engines are used to make games that could also be made with 3rd party engines and the game type is rarely the driving factor for that choice).