I'm a bit new to betting on UFC; I'm lucky I bet on McGregor for this match

Just a question, why does McGregor want Diaz to drop his weight? They're both equal at 77kg, so wouldn't the next match be unfair for Diaz if he loses weight? Will McGregor shed some pounds as well?
Either way, this fight was very entertaining to watch!
McGregor is naturally a lean guy with less muscle mass than that. 77kg is way too big for him, he was pushing himself to fight Nate at that weight. This cause him to start running out of cardio way faster than he would if he was lighter. That is why bodybuilders have poor stamina in fights and stuff like that, moving the extra weight is demanding on the body.
The odds for the next gamble in Diaz vs McGregor 3 are in favor of McGregor since he will be at the weight he feels himself more comfortable at.
Do you think that McGregors terms are fair? If not, why would Diaz accept? Does Diaz get to have some say or is the next match all on Connors turf?