That is a primary motivation and I have seen and read and experienced nothing to see that it is anything different.Not really ... just working from what he says — everyone acts out of self-interest.
Christians for example (and I was one for over a decade so I can say what I like about it), are primarily into the christian trip as they do not wish to roast in hell.
They seek the reward of heaven and immortality in the better place.
How is that not self-interest?
How many christians do you think are christians for any other reason?
Why do people breath or eat or comb their hair, or blow their nose?
Do unto others as you would......have them do unto you.
And how can you love another until you know how to love yourself?