so? most founders are doing that without pay, without a budget, and (most importantly) without the credibility that comes from the org/lab/prof

It's apples and oranges.

If a founder is successful they stand to earn billions in intellectual property value, not to mention the income from the product itself.

PHD's earn practically no money even if they are succesful, apart from earning their degree. (Which has an abstract long-term monetary value)

Seems very different to me. Apart from this, PHD's are employees, while founders are... well... bosses ;)