Why do you want to start your own business? Or, if you have, why did you decide to put a lot on the line to do so? A similar question can be asked of those who have found their non-self-employment careers in life: Why?
As with any business, you are presumably starting it so that you can provide yourself with income. There may be other, altruistic reasons, but at the end of the day you need to pay both the business's and your own as well.