And if your rich diversifying from just a me to index fund makes a lot of sense hint if the Rothschild's and other mega rich families run actively managed funds its probably a good idea for you to - I have done very nicely out of RCP on the LSE
My point is that to "invest" that way in a high cost area is not the smartest move. It's better to buy conservative dividend paying stocks. But if one must "invest" in property it's better to buy 10 for $200k than 1 for $1M. I also didn't mention risk mitigation: the risk of loss on the former is lower.
I don't think that's strictly accurate, there's something for every budget in real estate investment world, from buying a small condo to rent out to sovereign-fund-level buildouts like Las Vegas CityCenter or LA Metropolis.
It's like saying that someone interested in stock investing would not be buying a few shares here and there, but instead go the Warren Buffett way and acquire entire companies to get synergies across industries.
There are income-oriented investors and multifamily income funds who buy primarily for cap rates.
As opposed to you owning the houses directly
There are well-known possible positives to owning but the negatives are vast too, especially compared to investing in an ultra-low-fee index fund in lieu of a house.
Owning a house also made more sense in an era in which a single worker expected to work for a single company at a single site for decades. In an era when two workers may work for a myriad of companies for ranges of six months to ten years, it makes a lot less sense.