“I know enough to do the thing,” is fine.

“I know enough about X,” is willful ignorance. But “I have reached the limit of my interest in X for now,” is subtly different and healthy because interests come and go.

But, you can’t keep up and feeling like you ever kept up is an illusion of youth. So my advice:

If you have to pick something to learn (because you do not know useful things to learn) consider things that have been around a while like Linux and JavaScript and C++ and RDBMS etc. because they probably aren’t going to stop being relevant. Good luck.