TL.DR :-)<p>The best reason to start a company is that you are obsessed with solving a problem-- there is some pressing issue that you need to fix, or some product that you need to exist. Don't chase hot new technologies or perceived market opportunities (especially not as a 21-year-old newbie to the real-world market). The road to a successful startup is so long and hard that, without insane levels of conviction, most will fail. Don't start a company for the sake of starting a company-- start one because you honestly believe that you have to.