Don't underestimate the value/reward/fun/etc that you can get from a fresh project. New problems, new development process, the chance to re-iterate past designs and architectures, integration with existing/old/legacy systems, and a host of other things.
That's my bit of advice to you on that, as it reads a bit like you're very comfortable and expecting it to stay that way for "decades to come".
I do work on my own projects that are fun and interesting. But nothing beats a regular, permanent high-earning job, no matter how boring it is. I personally know a couple of developers who are stressed financially after working for "fun" companies.
That's my bit of advice to you on that, as it reads a bit like you're very comfortable and expecting it to stay that way for "decades to come".