I can agree with that, as increased population will naturally increase the number of genuinely empathetic individuals. Given I'm a "fatalist", of course I also agree about the universe not giving a shit.I think a not-insignificant amount of people do care.
It's just that at some point you realize the universe doesn't give a fuck about anything, and stemming that tide of life going on is 99% fruitless, so only the truly passionate stick with it.
That or you get married and have kids and have to go paper chasing.
The time that would then be spent on bettering humanity goes to recharging your sanity so you can do it all again tomorrow