because they/we are more likely to have worked at one, and see how it actually works, or doesn't work.

same goes for any high stress, high risk business, like running a restaurant. if you've worked in one for years, you're more likely to succeed in running one yourself.

there is a running joke in the restaurant business about rich semi-retired professionals opening up a restaurant and failing miserably, because they simply don't realize how much work it is. they think because they're great home cooks and can throw an awesome dinner party, they can all of a sudden run a commercial kitchen and dining room. wrong. very, very wrong.

same goes with startups. most people fail because they don't understand how much work it is, and simply give up.