Maybe because renting forever is ultimately cheaper than buying a house, especially if you aren't able to save at a rate that you can buy a house at a reasonable time.
We had to pay ~$70k in closing costs, so it isn't /easy/ to just go and buy something, but one possible lesson is that if you spend your whole life renting you are subject to the whims of your landlord (especially if you don't have rent control) and could end up paying a lot more for a place to live then you would if you had bought. Of course, the buy to rent numbers alternate back and forth depending on market conditions, so that doesn't hold true all the time.
* - Lots of confounding variables here though. SF vs. Oakland, $650 a month for property taxes aren't accounted for in the monthly mortgage cost. But we have a 40'x 50' yard, a garage, no shared walls, easier parking, etc. So it's an individual choice, but even all in my house is much cheaper than an equivalent rental unit in SF (maybe even if you factor in a new roof every 20 years, other maintanence, etc...at least in these market conditions.)
The decision to own isn't a static one. Its a relationship between what a house costs and what renting costs and when its appropriate to make the move. On top of that, one needs to worry about what happens in 20-30 years. I'll be retired with a paid off home and a low property tax load due to a senior exemption. Lifelong renters will still need to pay full rent until their dying day. This can affect when or even if you retire.
There are other homeowners who have lost money, and some others who are doing even better than you. Individual stories don't tell us about aggregates.
It's pretty easy to get a rough idea of what is better in your area using a rent vs buy calculator the New York Times has a good one... http://www.nytimes.com/interactive/business/buy-rent-calcula...