I think these days an SF connection would be a boost to other books; I'm sure more people have read my two little detective puzzles because of the SF connection.
To my mind, the best SF addresses itself to problems of the here and now, or even to problems which have never been solved and never will be solved - I'm thinking of Philip K. Dick's work here, dealing with questions of reality, for example.
Anything can happen in SF. And the fact that nothing ever does happen in SF is only due to the poverty of our imaginations, we who write it or edit it or read it. But SF can in principle deal with anything.
I do write a little SF in my spare time.