I'd say it's not reasonable.

Yes, there's the perception bias that makes absolute evolutionary sense when you deal with the 'lion or stone' problem.

However we as species dominate the planet because we cooperate. Religions, national states etc. are all imaginary sets of rules to ensure even more efficient cooperation in large groups. And here's the problem: If you meet a new person with distrust he/she becomes more likely to actually act according to your expectation. Given that premise is true an individual distrusting each an everyone weakens its evolutionary fitness as it misses out many cooperation opportunities.

Another point: If we want to counter the assholes plan of monoplizing this worlds ressources in their few hands we urgently need to learn cooperation outside of state controles rule sets again... this sentiment is one of the core problems why the US is just taking Trumps shit and its population is far away from taking action: They're devided and told to not trust anyone anymore. On this basis no revolution can be build.

I think this is indeed a feature of the modern US system... and also the reason it will be succeeded by other societies not or less impended in their cooperation.

Cooperation beats competition in the long run any time.

As often in life the picture isn't black and white. The way I see it: Most people (~ 80 % or more) are decent. However we have egoists, narcissists and opportunists in our society. Unfortunately our current economic and societal system cultivate this sentiment and destill the most reckless undividuals into the highest roles (corrupt politicans, billionaires) where they assume everyone's jusg like them (who likes to see himself as outlier?) and hence make rules as if we were all assholes. With the benefit that it justifies their shitty behaviour... becaus ,,everyone else would do the same in my position". Well I say most people won't.

Durint COVID 10 - 20 % assholes where completly sufficient to empty stores out of greed (there never was an actual supply shortage after all). I once saw a woman in an expensive SUV carry a whole trunk of toilet paper to her house... which of course is anecdotal but fits my narrative.

On the other hand I saw many more people taking care of each other when going into isolation for example... in crysis the majortiy deepens its cooperation since it always more efficient than wasting ressouces in competition imho.