Or: humans do have that capacity, but our system is explicitly set up to give the most power to the greediest among us, and these greedy people in power don't have that capacity.
That will happen in any system as hierarchy is in human nature, throughout history.
Which means those greedy people don’t have power, but the illusion of power, and the positions at the top are gatekept by intermediaries that serve the one who actually holds the power.
On no other issue would this type of wishful thinking be accepted.
If I pour some water in a bucket and come back to find it's all leaked out, and do this every day for all of human history and always get the same result, I don't conclude the water wouldn't leak if it just tried a little harder.
There's a hole in the bucket.