Agreed.
The main reason people “do good” is because they know what it feels like when someone else helps them, forgives them, or spreads goodwill or generosity. And / or they want the world to be made a better place.
The second reason, is similar to the above, but they want other people to like them.
The closest “spiritual’ reason I encounter, is that a lot of people believe that the good and the bad that you do will come back to you, such as Karma, or a way of things balancing out. I personally do not hold this view. You can be ‘good’ even sincerely and maybe all you get is people taking advantage of you. That doesn’t mean you stop being helpful or generous, however; If you are, you’re stuck with being a ‘good’ person regardless of rewards or lack thereof.
As far as Christianity is concerned, people want to please God, but probably do not fear Hell. Most people who believe in the Christian God believe they are saved by Grace. They do good in order to please God. More out of gratitude.