I have no doubt it is complicated.
I would argue one important strategy is to separate the people responsible for
creating the weapons from those responsible for deciding if/how they should be used.
It's noble that Oppenheimer deeply regretted what he had helped create after the
fact, but there were many that were quite aware of what was happening, and
made public warnings to that effect (Einstein for one, 6 years before this historic
event.) As you say, Oppenheimer was known to have a big ego. This wasn't the
first time he quoted from the Bhagavad Gita. But what would you expect? He was
a genius, separated intellectually from those around him. Teller is another
useful case.
Nuclear war protesters played an important role. If nothing else they were one
voice of sanity in a world apparently hell bent on destroying itself. I'm not sure
you give them proper credit here. Many of them were prominent scientists, yes,
maybe there were some C students out there, but they had their share of
Valedictorians out there too... :)
Scott