If the founders were such as well off already, then then taking risk in the same quantity of time and/or money isn't the same as the employee trekking the same amount of time/money. The founders that are well off can easily move on after failure, but the employee have lost out (it's not very useful to list a failed company in your resume).
If they are well off already then they, as individuals, are well off which has nothing to do with whether they are founders or not. Rich people have more options than poor people.
There are rich people who work at companies too who won't be bothered by failure while the founder who came from nothing will be hurt.
