Your first teacher is your most important one.

Usually people think to themselves "I don't know anything about playing the piano, so I don't need an expert."

Unfortunately, this is incorrect. When learning any instrument, the skills involved are complex and it is very easy to learn to play with bad habits. Improper form, excess tension, and inefficient practicing techniques are very easy things to happen if you don't have the proper guidance.

The more you master the instrument, the more you are able to make the kind of music you want. With bad habits, your progress is frustrated and eliminating bad habits is hard.

The biggest reason I can play as well as I do is due to the expert guidance I received from my first piano teacher, Margorie Haimbach. She knew how to motivate me and give me the skills I needed later on when I went to further study.

Even if you are studying piano simply for your own benefit, the same principles apply. Don't be lured into thinking "Well, I don't want to be a concert pianist... so..."  Whether or not you are professional, your satisfaction from performing is only enhanced by proper early guidance.