This is a question about ethics (and probably may not have a strict answer).

As a user I prefer (especially when the question is 'foggy'), to add a comment proposing an answer or giving hints towards an answer than posting an answer. If my comment is the answer I will later post it as one.

The issue I encounter, in many cases, is the following :
A 3rd user takes my comment and posts it as an answer, the answer is accepted and he takes all the credit (I do not mean the rep point). So is this kind of behaviour ethical, to replicate someone else's' comment and post it as an answer? Can we avoid this kind of situation (e.g. flagging somehow the answer).

I understand (but I not accept) this kind of behaviour from new users since they may doing it just to build reputation, which is still wrong. But what about user with hundreds of rep point, what do they have to earn?