Restaurants, bakeries, hair and nail salons are not startups and do not do product development. Their market is known before the business is opened. Running one of those businesses is extremely different than a tech startup, where the risk is from not knowing what the market will be for the product in development.

(And you should know that, given that this message board you caters to the startup crowd, and is sponsored by a company that educates people on how to run a startup.)

I encourage you to read through YCombinator's "startup school" materials to understand the fundamental difference.