Where do we draw the line? What is right from wrong? If everyone kicks out religion and lives for themselves, at what point is there absolute chaos?
Most people have an irrational desire to be liked. You can't be liked, if you don't minister to other people's needs, to some extent. Also, in absolute chaos, your health starts to deteriorate. There is only so much boozing you can do, before you get sick of being sick, or perhaps observe that it's better not to booze in the first place, by observing others. There is a limit to how much you can live for yourself, before your life becomes totally meaningless, or find that there is no food in the fridge. Most people observe that they have some talent, and resolve to get meaning through developing their talents.
There pretty much has to be an irrational core to our bothering to exist. Some atheist cultures show that the world does not fall apart without religion. We managed to get to this point, without religion. Chimps and Bonobos also do fine without it.