Without any statistics at all to back this comment, I bet there are a magnitures more software companies out there that have made people 100% of a million, vs 10% of a billon. You're talking such a small pool (which might seem large in HN terms) when in reality there's an incredible number of small software companies globally.
Of course not discouraging anyone from shooting for the moon.
After we signed with a vendor, the owner took us out on his boat one weekend. As we walked through the harbor he pointed out all the other boats owned by competitors and other companies in the same industry. "This is Supercom's boat, this boat is owned by the person that started Megacom, and that's Supercom's old boat and now it's owned by the Digicom guy..."