His X.com/paypal was not based on his previous wealth and corresponds to the thing that propelled him to later successes.
I'm not actually saying that he's not a great business tycoon, he clearly is based on track record. Plenty of people have the kind of base resources he had without amounting to anything. Either they don't bother to even try or are too stupid or too unlucky too succeed. His parents wealth is still the catapult that launched him to his current success.
There are plenty of people who could have done what he's done but did not because of lack of resources.
With X.com he did quite a bit than invest as all of the other cofounders left prior to launch. By the time they merged with cofinity Elon was the only one of the original team.
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.