It's obviously true that nobody achieves things in a vacuum, since we all have some level of "privilege" given to us by our economic circumstances, the level of education available to us, our luckier heritable traits, etc. But for every successful person, there are countless others born to a similar level of privilege who squandered it. The claim that everyone owes their successes to the group ignores this.
If you were to truly do a science of people would you not take into account all of the circumstances that person was in, in order to understand them? You say: "One achieved it, but the other person in similar circumstances didn't achieve it" Well how do their circumstances differ? Don't you think it's important how they differ? Actually, couldn't how they differ be the key? Why, then, do you draw the line at an incom…
I would think the correct level of analysis for this conversation is the lowest one that still allows people to be accountable for their own actions. Lower than that, and the central question of this thread is irrelevant.