If people do a lot of things for others and it makes them feel good about themselves, are they doing it for selfish reasons?

Customers will only ever buy from you because they care about how the product or services will make themselves feel. For example, if Princess Mary is wearing XIII and you wear XIII, you are not wearing XIII because you like Princess Mary. You are wearing XIII because you think you’ll look better in the eyes of your friends and family because you are wearing something that Princess Mary is wearing. It’s for you that you are doing it, it’s not because of Princess Mary, it’s your narrative.
For more about XIII, see www.xiii.dk