Is this real for you reading this?

So, I was talking to a friend yesterday, telling him a problem of mine, and suddenly he told me that people don't do things for me because they're expecting something in return. He said that they do it because they want to do something nice for me, and that's it. But I genuinely don't believe him because all this time I was doing things to be a good friend, a good girlfriend, and everything I did was so eventually I wouldn't be called a bad person, so all this time I've been living in a lie??? Or is he too kind for this world??? Am I wrong for thinking like this??? Do people actually do things Selflessly? It'd be nice to have that mindset, but deep inside I know people like me because of the things I've done, and not because of other nice/kind intention.