Claiming success is a social construct seems to me to be trivially true, not a staggering claim. Intelligence is less obvious since there is a vast literature around it, but, again, it is clearly a social construct; we must struggle to agree on a useful definition of intelligence, therefore it is a social construct.

I'm also not sure what "scientific evidence" would look like here. You seem to have had some sort of allergic reaction to the assertion of social construction and retreated instinctively to familiar but hollow epistemic grounds.