Actually, I think they just took the contrapositive and just didn't spell that out explicitly, which is not super helpful.

Okay, but why is there no flipping happening in the two parts of the sentence, if it is a negate necessary / negate sufficient? And if there was a lesson about not flipping the two parts if there is a group 3 and a group 4 indicator, where is that?

Actually, never mind. It would have helped if someone could have explicitly spelled out that the contrapositive was taken.

I would also like to know the answer to this question, because even with the explanations, question 2 does not make sense to me.

I amend my statement. There are actually three different options that comparison could imply. Either way, the idea of a winner could potentially obscure those three options.

To be honest that still does not make any sense to me. The first part of the sentence has direct implications for the comparison. If you are trying to parse out the meaning of the sentence, then implying that there is a winner makes the actual meaning of the sentence in context (that it either could be equally likely that people act unselfishly vs selfishly OR acting unselfishly is more likely) more confusing. I think that means you could potentially miss the meaning of the sentence as a whole, and get the entire question wrong on the LSAT.