Reading a biography mostly informed me about the lack of general empathy, remorse, sympathy. Only regret came forward a little (and only once).
> be crazy enough to bet it all
Anyone who doesn't suffer any real consequences. Having parents with a lot of money makes it not matter all that much.
As for the other bad decisions; it doesn't really show much positive except maybe persistence, but persistence in a vacuum is not a good thing. In a way, it mostly read like "a skewed mind made a bunch of bets and got lucky". Perhaps mostly an example of survivorship bias in a business sense.
Now, if we go back to the hoarding; it's not about when someone didn't hoard, it's about the here and now. I'm pretty sure we can find a period of time where Gates or Kamprad didn't do any hoarding, or not the hoarding we'd expect. But concentration of anything doesn't really happen by accident, and wherever we see it now, we can assume it was intentional.
There are of course also examples of people on their death bed realising their hoard doesn't really matter anymore and they might give most or all of it away. But that doesn't mean the hoarding never happened. It doesn't turn someone into a genius or a saint. When such things happen, we might consider it commendable, but that doesn't mean history disappears.
In a way it works not like a balance or a sum but more like a ratchet; it's about the degree to which someone hoarded stuff and how they acted with their hoard (doesn't have to be money, can be property or secrets or power or knowledge etc).