I ask you this question regularly, because there are several possible answers.
It may be by obligation (you just lost your job);
It may be an idea of genius that goes through your head;
It may be that you are a control freak;
It may be that you want to be rich;
In short, there are several reasons, but one of the reasons that is most important is the desire to create.
The desire for creation is so strong that it is the feeling that makes us happiest.
Just think of Ikea, you get a piece of furniture in spare parts; we are discouraged; we are sacred; we put it up ... we just created something. And it is appropriate: "darling come to see MY furniture"; One is happy.
And with hindsight, it's a bit like what you're most looking for as an entrepreneur: to be happy!
Create makes us happy and with a little luck: rich