>My experience is that if people are in an environment where helping others is socially encouraged rather than punished, most people want to help even strangers providing no benefit to themselves other than the healthy little dopamine hit. There's exceptions of course, but not enough to actually cause a problem.

What they stand to gain in that situation is good standing in their peer group which is a personal gain. It's basically personal public relations management.

How often do people truly do something good without standing anything to gain? That is the true measure of innate human tendency to doing good. I'm sure there is some of that, but very little.