Do you actually finish the games? I’ve tried the DIY game engine approach before, but I never have finished a substantial game before because I get caught up in the weeds.
Granted, I haven't finished my game this way, but the engine isn't really the bottleneck. It's deciding on, and implementing, appropriate behaviors, often for silly, fiddly corner cases.
The main issue is that I make most of the game, then realize that it’s really unbalanced and the controls are clunky and it isn’t that fun. So i lose interest. Probably related, I don’t really enjoy video games anymore because I get bored too easily.
Also, you could just go work as an engine programmer in AAA or for Unity/Unreal/etc....