Symptoms of low T for me are difficulty sleeping, migraines, low sex drive and overall low energy. But it doesn’t take a whole lot to get me out of that range; just a tiny dab of gel rubbed in to my shoulder (for comparison, a man with low T would use an entire 1g tube every day). Low T that’s not super low doesn’t necessarily make any of that worse, and very high levels of T will actually convert into estrogen (which is why bodybuilders who abuse steroids can grow breasts and have shrunken genitals, and also increases emotional volatility).

And I think you’re right; there is a population benefit to lower levels of testosterone overall at a societal level that reduces conflict. Furthermore high T levels have a positive feedback loop with physical labor (building muscle is way easier the more T you have), so it makes sense your body would produce less if it isn’t trying to constantly repair muscle damage from strenuous physical activity. I would say that high T levels would be a liability in an office job; they make people quicker to anger and outright aggression is not taken positively in knowledge work. There may be benefits for physical labor, but definitely diminishing returns if you work a desk job.