Gates & Allen were able to generate revenue almost from day one, to cover expenses for the business.
Your theory is also decimated by Paul Allen.
Those two never had to worry about starving to death, because they made sure to generate sales from the very beginning. Microsoft was started for peanuts, they lived on peanuts in New Mexico, they drove sales, and that was that. It would not have mattered if it was two Paul Allen's coming from a middle class background, or a Gates and Allen. One thing mattered: sales.
You know why Allen wasn't afraid, despite lacking the Gates family money? He knew he had the ability to go get a well paying job at dozens of companies, he had a valuable skill.