We're going in circles here. Yes a demand must exist before a business can exist to meet it, the other half of that is that someone with enough wealth needs to start the business, or expand a pre-existing business, or invest in new technologies to meet a certain new demand etc.
It does depend on how one defines "rich" of course, to be considered as in the 1% in America you need to roughly be worth around 400k annually, and that can be an individual's earnings or an entire family's.
Small businesses in America create roughly 60% of all new jobs in the private sector, this doesn't take into account how long those jobs last.
Minimum wage laws are tricky. On one hand it ensures that people will be paid some sort of standard living wage, and also allows people to have security by knowing that no matter what happens they'll get a set amount. On the other hand it creates a barrier to entry for lower class people and minorities. Why would an employer take a $15 per hour risk with someone right out of high school, no experience over someone with a lot of experience and is an adult, or white, or a man etc?