Can someone explain to me the financial sense of buying in San Francisco?

I see many rentals for $8k-10k/month that are often rent controlled which buys you very nice benefits... These are 3-4 bed and 2+ bath rentals of 1500+ sqft that would go for lets say $1.8m on the open market.

Comparing the math...
- $1.8m, even if you were to do 0 down with no PMI, which is impossible, at a 6% interest rate would be ~$110k in interest a year or ~$9.2k a month
- Property tax would be ~$1.9k a month
- HOA + Homeowners Insurance is $600/month

At this rate, you are looking at near $12k/month in costs going to 3rd parties... Even if you were to pay cash for a $1.8m place, you are looking at that $1.8m place earning likely ~3% a year in gains versus your $1.8m in the stock market earning ~8% a year in gains, so you'd still have a delta of $90k/year ($1.8m * 5%) that you'd otherwise have made through renting instead of buying in all cash. Let's compare that scenario for a minute and assume a 10 year hold period:

• $1.8m in stock market after 10 years = ~$3.9m
  
• $1.8m in real estate after 10 years = ~$2.4m - plus once you sell, you are going to incur ~6% selling costs, so in reality it is more like $2.2-2.3m... Even though it is tax free...

Why do people buy versus rent? You get way more flexibility out of renting & financially it makes a lot more sense... Available inventory is the only reason that I can think of...