Its only appropriate to compare returns against the sp500 if you are taking on exactly the same amount(and type) of risk as the sp500.
By this bad logic, bonds are a terrible investment and nobody should ever buy them because the s500 is better.
Same goes for owning private companies, although it is murkier to see.
A single company is always going to be riskier and more volatile than the sp500.
I wouldn't necessarily characterize Dell as an idiot though. :)
In the last year I have met 4 billionaires - and what I have observed was that above a certain level of extreme wealth it’s not about just making more money, it’s about forfilling autonomy, mastery and purpose, which might mean a non-optimal financial strategy, but is rewarding in other ways.
One can invest, take risks, and fail. Doesn’t make you an idiot. Majority of startups fail. Doesn’t mean the founders are idiots.
You aren't an entrepreneur, are you?
A huge part of the economy of Austin is Dell and I am sure he likes being part of the action and an engine for the local economy and his employees.
If you're worse off than an S&P index fund then you're not a genius - you're an idiot.