Hedge fund, million to billion?

Been reading a bit about the backgrounds behind some notable hedge funds, and my general question is - how does a no-name manager starting a fund with single-digit millions or less goes on to manage a billion+ within a decade?

Obviously the direct answer is something like "He does really well, makes the right connections, and gets big time investors" but I was wondering if anyone had anything more substantive from memory or experience.

Examples include:
Einhorn moving to NYC with $900,000 in 1996
Ackman starting with a few million in 1993
Loeb starting with a few million circa the same time

I'm sure there are quite a few brilliant guys out there that have struck out on their own with a few million bucks and have been putting up 20%+ returns in their first 4-5 years, but what was it about those 3 I named, or others that took a similar trajectory, that saw them managing billions a decade or so later?

And has the possibility for this trajectory (assuming you do put up good returns out of the box) changed for someone equally talented and unheard of starting out with a few million today?

Thanks