Actually, it's not as simple as Sixties types "selling out" or, as the conservative response to their regression would put it "getting all that foolishness out of their heads".

Sixties consciousness and activism, on the mass level, was actively & explicitly crushed by the U.S. government and governments allied with it- and opposed to it, such as the Soviet government, which some conservatives still like to pretend was "left-wing" for some reason- by various methods, ranging from, essentially, the threat of a new round of "blacklisting" for white activists and counterculture figures who did not recant, to the out and out murder of a generation of radical Black and Brown and Indigenous activists.

People didn't "grow out of" "grow up from" or "let go of" Sixties activism, including the more political forms of "hippie" activism- they had it threatened beaten or KILLED out of them.