If a rich great childhood was sufficient to build great businesses, then shouldn't we expect a middle-class childhood to be sufficient to build a decent business?

But a lot of middle-class people try and fail to create any kind of business.

The reason is that it takes more than money and education to build a business.

Money and education are necessary to build a great business, like electricity is for your home, but insufficient, as your home also needs good construction, running water, etc.