"He is probably wealthy."
Translation:Il est probablement riche.
So, peut-être also can mean "probably" - seems like quite a stretch between possibly and probably.
Why would "il est surement riche" be a possible translation of "he is probably wealthy"? I would think surement indicates certainty that probablement/probably doesn't.
Depending on context, the adverb can also be at the beginning and even at the end of the sentence