The boomers were unique in the way material conditions cultivated that selfishness. Their parents and grandparents left conditions better than they were given.

Except Boomers all have lead poisoning from growing up around leaded gasoline, which means their generation is uniquely antagonistic, selfish, and stupid. This is not an "every generation" thing, there is an actual reason their generation is so short-sighted, uncaring of future generations, and has fucked everything up.

You're ignoring nuance. Humans in general are selfish. Boomers are selfish humans.