I feel like a lot of people here are trying to say math things without actually doing any math. And comparing home insurance to the lotto is dumb. If anyone really believes that insurance is like the lotto, well then I guess we should all just stop paying insurance because we're all morons handing money to billionaires.
Granted that Colorado is a pretty safe state for homes, so I don't feel like there is a huge potential for loss. But there are a lot of big ticket items that can be covered. (But hopefully MMM has personal liability insurance to protect his investments and other assets.)
But let's make some extremes here. If home insurance for a $400k house was $1/yr. Everyone would be saying that MMM is an idiot for not taking that deal. It doesn't even matter if he can self-insure or not, a $1/yr premium is a smokin deal that would pay itself off likely 1000's of times over. So it's not that once you have enough money you just shouldn't bother. You should evaluate for yourself what is worth it, and what isn't.
I don't take C&C insurance on my car because the additional cost of about $300-400 per year pays itself off in 4-5 years, and since it would not be financially devestating to my bottom line to take that hit, I feel comfortable taking that bet. So if Home insurance were $20k/yr, I think we would all agree that the odds of that paying off are extremely low and is not worth it.
And yes a lot of insurance companies make a lot of money. There's also a lot that don't make money, especially after a big disaster. Which is why insurance companies purchase reinsurance, because there are times when they don't get expected loss right. Actuary tables are not perfect; both parties in the exchange are taking a bet.
Now I'm going to guess that home insurance is going to cost about $1500/yr for him. And let's just do some expected loss calculations on just total loss of home (so it's not the full benefit of the insurance, but it's easier to examine it in isolation)
$400k * (chance of total loss) = $1500
So here we're estimating the chance of total home loss to be about .3%. Or in other words, you're paying .3% of the value of your home to protect the other 99.7% each year.
Since MMM's only likely source of loss is Fire (maybe hail, but that wouldn't cause total loss). I looked up the Fire statistics. There were 365,500 house fires last year and 124.6 million homes. That means about .29% of homes each year catch on fire. Seeing as home insurance covers more than just house fires, if his home insurance is $1500/yr, I would definitely say he is making a bad deal, and being on the wrong side of that deal is a huge loss. MMM's wealth status or not, you take this deal.