A lot of life is a trade off. A lot of it is a zero sum game between you and others’ happiness. People would agree that ideally we’d want peak happiness. But in order to achieve that we would have to efficiently balance the trade off between what makes us happy verses what makes the group happy. An example below is from economics called a Laffer Curve which basically wants to figure out how to optimize governmental revenue given various tax rates (as too high taxes will strangle economic growth and too low taxes will bankrupt the treasury). In the case below we are modifying it for happiness. If everybody’s too altruistic it will produce an unhappy society because everyone will be putting others first and not attending to their needs. However, if everyone is maximizing for their personal happiness (which we are more toward now) then there comes a point similar to tragedy of the commons where the gains in personal happiness come at the expense of the group’s collective happiness.
For example if a group of friends is going out to a restaurant but one of the people is taking too much time and making everyone else late. Or people blasting music without caring about how their neighbors feel. Yes your selfish action makes you happier in the short term but your happiness is diminished by the selfish actions of those around you.
I posit that in the 60’s we had a better balance of personal happiness verses collective happiness and that’s why that decade is remembered so fondly. People were altruistic to an extent but they were also about finding themselves. Now the pendulum has swung way to the individual happiness end. Selfishness has become normalized and the few forces pushing against it are weak. But people are more unhappy because dealing with the fallout of others’ selfishness is more of a drag on people’s happiness than the happiness they receive from putting them self first.