I talked to a guy that became property millionaire, if I had followed the exact same step he took, just with 2 years difference and a different city, I would have been in bankruptcy right now. You didn't/couldn't take a loan when they did - that boat has sailed. Buying today is a different market and you should approach it ignoring what you friends did in the past.
I won't give you market advise as I don't have a crystal ball. However, as a renter you are free to move around - that's your strength. Alternative to buying is therefore to move around and maximize your bang per rental buck. In most cities, there are areas where people would rather rent than buy and vice versa. Try to rent in the place where the rental yield is the minimum. Also, you have can look for better job opportunities that requires moving.
And even though real-estate value has increased a lot. Rental income from these properties didn't increase at the same rate. Tenants can't afford to pay rent landlords would like to charge so there is downwards pressure on returns these properties can generate.
Not to mention, interest rates are at record low. What's going to happen when they go up? Not only demand for real-estate will be lower, there are borrowers who have accumulated too much debt to buy real-estate. They might be simply forced to sell as they wouldn't be able to service their loans anymore.
Nobody can predict the future but I'm not going to be surprised if we witness another real-estate crash in 2-3 years.
For this purpose, it's a minimum-risk store of wealth with a potential for appreciation and any actual returns are less of a priority. Something similar applies to Saudi and Russian oil wealth; an escape from the possibility of SHTF.
Except often they don't, rental income is almost like a rounding error to them (it's not really, but they can't be bothered - the main thing, it seems, is buying the asset.)
When interest rates spike, landlords lose leverage ability and may even have to refinance their loans. Spiking interest rates will lead to an influx of homes into the market as landlords who did not plan well enough for the spike are caught underwater in the same way as residential homeowners were in 2008.
Private equity firms are backing the loans, so maybe they'll just take the houses when interest rates spike, and rent them to tenants themselves. In the future, we'll all be renting from the Blackstone group!
Disclaimer: I am very uninformed on this subject and do not know what I'm talking about. :)