Gale saw all the Weave had to offer and felt he wasn't good enough. Imposter syndrome next to a god. Him wanting to be a better wizard (have more magical power) is never the issue, the way he tries to get there quickly is.
Except none of that is true.
He didn't see all the Weave had to offer. That's literally the point. Mystra was keeping part of the weave away from mortals due to it being hilariously unsafe for them.
Gale wanted to access this part of the weave. This is the reason for him and Mystra falling out and why Gale went to go and get the Orb to return it to her as a gift to make nice again.
He outright states this in Act 1 upon him revealing the Orb to you (Rather, as a preamble to revealing the Orb) either after giving him 3 magic items or by bringing Elminster to see him.
As for Wyll, when he is torn between saving himself and his father in act 3, the basis of his dilemma is that he believes that he needs Mizora to save his father. When you tell him that you'll find and rescue Ulder without Mizora's help, he thinks it's futil.
Except this isn't about needing the "Power" from the pact. This is about Mizora giving him an offer; whereby Wyll gets locked into an eternal pact with Mizora in exchange for the information about his father's location.
Wyll is perfectly capable without the pact. As I mentioned, he states not wanting to be in the pact in Act 1 and is annoyed at the pact still persisting for some time after it is agreed for it to end in Act 2.
In fact, this is literally the reason why the Act 3 "Dilemma" is even a dilemma. He doesn't
WANT to be in a pact with Mizora because he doesn't
NEED to be.
