When Microsoft went public, Bill Gates owned 80% of the stock. His wealth, compared to other tech company founders, is essentially all the product of not getting diluted.

Microsoft did not have the "full faith and credit" of the Gates family. His family figured it would burn out and he'd return to college, per what Bill has said on the matter. They were less than thrilled with him dropping out. He received $0 funding or help from them in regards to Microsoft getting started.

It was a million dollar business, completely independent of the Gates family or its connections, while it was operating in New Mexico. Bill and Paul had sales almost from day one.