Don't worry about that. The thing you'd want to worry about, if anything, is spending years just grinding away in your one little niche.

Lots of old people start companies, but the key to success is having a wide variety of experience, and not being afraid to get more (like sales! like marketing! and so on!).

You can do it! (I did! And just landed my 4th customer for a high-dollar-value subscription service!)