I think the type of people who shouldn't start a business are those who need stability and predictability, and who aren't comfortable wearing many hats. There's nothing wrong with being someone who isn't business-oriented, it doesn't mean they aren't hardworking. However, individuals who are highly specialised in one certain area might find it challenging to adapt to the uncertain terrain of entrepreneurship. That being said, anyone can try to start a business by learning the skills needed and being able to delegate tasks. It's not really off-limits for anyone, but your success really depends if you're the type of person who thrives when working for yourself.

Absolutely - If you aren't prepared to do what it takes to make it a success..  If you don't have the confidence that you can really make it... There are lots of people and lots of reasons.