I read a forum thread last night with some DMs talking back and forth. I think the context was whether they were “good enough” to DM professionally.
A lot of people said encouraging things like “You’re ‘good enough’ for your group; that’s what matters.”
I kinda disagree.
Why not strive to be the absolute best you can be? Every week, stretch your comfort zone in some way to consciously work to make yourself a better DM.
All of this is constrained by the time you allot to it, of course. But don’t ever feel like you shouldn’t work harder to improve yourself simply because your group is already having fun.
No matter how good you are as a DM, you can always improve.
Now get out there and tell a story!