I was using SF because it's known to have had a much higher house price inflation than other places, in order to try to be charitable to your case. If you look at the overall US housing market then you need to go back a lot further than a decade to see 100% inflation.
actually I tracked housing prices directly here in California on a large scale.. the key to resolving the two positions here is that, volatility is exactly how a one hundred percent increase in price happens.. first drop, the rise, then drop a lot, then rise alot. Meanwhile in the most desirable a.k.a. most expensive zip codes (or similar). the rise has been steady, even at 2008, and as you say, not one hundred percent. Lastly, ordinary people like you and I are not privileged to see the vast amount of cheating that goes on with residential valuation, loans and the like. Loans for more than a realistic value on a property, are as old as Sicily.