As an individual looking to make long term investments, I'd still much rather own stock in Berkshire Hathaway because its holdings are much more diverse than just Facebook stock. FB is not as safe a long term bet for the average person.
The average person should just own a stock index fund. In fact, this is the exact advice that Buffett gives.
So we're comparing someone who is 87 years old and has steadily increased their wealth over time, to someone who basically got rich very quickly, and whose wealth is open to extreme fluctuations.
I'd much rather be the first person.
You can argue that he is so rich exactly because he didn't diversify.
Obligatory Warren Buffett quote: "Keep all your eggs in one basket, but watch that basket closely"
If this is a "virtue of work" thing where Buffett is somehow "better" because he "earned" his money I don't buy it. Being the son of a wealthy politician and using that influence and money to procure MORE wealth and influence isn't somehow more noble than creating one of the most powerful companies in the world.
But I mean, if you're more into the whole "old money" crowd, that's your choice I guess.
I get that humans are, by design, way too risk averse, but what do you define "could easily go under" as meaning? What odds would you actually give of these outcomes: Facebook keeps stays a top 10 business for the next 20 years, Facebook stays a top 10 business for the next 5 years, Facebook implodes and is worthless in the next 5 years.
I get your point, which I think is extremely narrow, is that "a diverse portfolio is better than a single stack investment plan", but to say you'd prefer to be one billionaire vs being another different billionaire because the first billionaire meets some weird criteria you've devised for determining how best to become a billionaire is not an objective point to be made.
TL-dr; you're not playing the same game either of these guys are, and your suggestion that trying to model your life after one vs the other is a weak point to make because of it.