I think this is easy to explain scientifically. If one spends money on other people, those people will express genuine feelings of happiness. Seeing those facia

I think this is easy to explain scientifically. If one spends money on other people, those people will express genuine feelings of happiness. Seeing those facial expressions of happiness will activate 'mirror neurons' which in kind secrete dopamine. Afterward it simply becomes a feedback loop, ie: the more money you spend on people (different people), the more often you are happy.