Some people just like to feel superior I think.They feed off of helping those they think are 'less than' them.

I have a friend like that,always telling me what I should or shouldn't do,always trying to do things for me,always trying to jump in and take over.It's getting to the point where I don't even really want to talk to her anymore because even simple things I say,like when I said I needed to buy a new Christmas tree ,she started saying she would go buy one and drop it off to me.It gets annoying,and I am realizing that she thrives on feeling she is superior.

And some people,like my husband,are just people pleasers and derive self esteem by being liked by everyone,want that pat on the back all the time,want to hear how helpful and kind they are,it makes them feel good about themselves.

I am sure there's many other reasons,but those were the first two I thought of.