"I've come to the conclusion that the best tech company leaders were those that built up a company from scratch."
The leadership that is required to bootstrap a company to a few $M is typically not the leadership you need to take it to $G.
The hard part is for the company leader to see that the company has now outgrown their strengths and put the company in new hands. Far too many try to keep their oar in, wrecking the process.
That is what BillG did. He didn't look for a fresh new leader. He handed control to his buddy Ballmer and kept steering the company from chairman. Now BillG remains on the board as technical whatever, so he's still trying to keep MS in a path of his making.
I've worked with a few companies that transitioned well, but there was normally some pain. In the end there is normally a huge fight and the ex-leader cashes in all his stock and leaves the company of his making entirely.