When I post an answer as a comment, I take the risk that my comment will eventually be deleted. But comment deletions are not so quick nor frequent, and my comment will most probably be read and taken into account before it happens.
On the other hand, when I post an answer as a real answer, I take the risk of being downvoted and loosing reputation points. Once I will have thousands of reputation points I think I won't really care about it anymore. But currently I am still low rep and I have to pay attention to this possibility. When I was under 50 it was even more important because not being able to comment really sucks and the tiniest little rep point is important.
There are strict rules for downvoting answers, for example they must be nonconstructive or offtopic. But experience shows that among high-rep users who don't care anymore about the rep, some won't hesitate to downvote just because they don't like it, even if the response is constructive and ontopic, exactly as if they were on META where you are allowed to proceed like this.
Since I ask myself a lot of questions, I am the first happy that there are so much competent people that can make very complete and detailed answers. But when I am in the position of answering, I know that there is a high probability that a "Thousand goldish" user will post something three times better and more detailed and get most upvotes.
Once again I won't complain about this since it helped me so much in the game so far. And I am even more sorry that I don't exactly conforms to the rules, but most of the time I'd rather leave my two cents in a comment or say nothing, rather than taking the trouble of posting a useless answer that might even grant me downvotes