There is nothing wrong with doing stuff just for fun.

There is nothing wrong with being focused on just few issues.

But I have doubts when you claim some knowledge without being able to use it practically, which is what I see here.

If I'd say I'm jack of all trades, as I'm interrsted in software - but i hire a guy to make all the code for me because I don't know how - and that I'm very interested in knives - but my wife sharpens our knives as I don't know how - I have doubts about your actual knowledge if those fields.