It takes about 1-2 years to get decent profit flowing in a startup, so if you can live 5-6 years, then quit and try for 2.

You will grow so much during this time that if you had to go back into employment, you could command a much higher salary.

But this only applies if you are a self-starter. Once I stopped working a full-time job (i.e. employment) and started my startup, I actually do a lot more hours. I dont notice it, but I do. It's not for everybody.