Good point, however I don't know if I agree actually. That's looking at a human in a very simplistic way, which probably means it isn't fully true.

For example humans live (and always have lived) to a relative old age, well past their prime and past the point where they can produce offspring. Even back when the average life expectancy was low, people still easily lived to 50 years old. It's just that a high infant mortality and death due to accidents and illness pushed the number down, a single human could easily live to be 50. At this age they don't work as hard, can't produce offspring and can't really compete, so why keep them around? Many other species don't live that long or are even actively killed off. The theory is with humans being very social creatures, always working together to outcompete everything else, keeping the older ones around must serve some kind of benefit. It is thought they could no longer work hard in terms of hunting and gathering, they could still look after offspring whilst the rest does those tasks. They could also do smaller, less demanding tasks and so still contribute. This made them earn their keep so to speak, providing more benefits than the extra resources they consume. This meant a group which had elders around had a better chance of survival than a group which didn't or had less of them. Thus there was an evolutionary gain to living into old age and it was selected for, giving humans (and other hominids who we are related to) a much longer lifespan than one would otherwise expect.

This means being lazy to conserve energy isn't the full story, there's also the social aspect. Someone contributing to a tribe not only helps boost the survival of that tribe and therefor themselves, it also helps them not be ousted from the tribe and thus significantly decreasing survival odds. This means going the extra mile for the tribe, even self-sacrifice, would be selected for in terms of evolution.

Another side would be I expect a modern human to be slightly more advanced than our hominid cousins and not be driven purely by instinct. We live in a society with rules and expectations and it's a conscience choice whether to adhere to them or ignore them. It is generally accepted that in normal circumstances a person is fully responsible for every action they do or do not undertake.

But the theme I've noticed is people are caring less and less about society and more and more about their own bubble, so in that sense they might not be malicious. They might be driven by this general trend and the causes for them, which I'm unable to speak of with any kind of expertise. I shared my personal experience, which might or might not be reflected by reality.

But thank you for shining your light on this, I agree the term assholes implies it's malicious.