i think you are right, Terry, in theory. But the theory doesn't work so well in real estate. Allow me to explain.
Trading stocks increases the risk to a portfolio versus buy-and-hold. The risk is based on calling the timing correctly, which few if any have perfected.
That risk increases thousand-fold with real estate because real estate is not a liquid asset. You cannot wake up in the morning and sell your real estate like you can with stocks. The 2008 crash came so quick it would have been extremely difficult to get out in time. Banks shut down their funding pipelines so even if you could find a willing buyer that person could not get the money to purchase.
That was an anomaly that hopefully won't happen again. But it may! Even in a regular market the market can change dramatically (for or against you) in the 60+ days it takes you to list and sell a property.
Assessing risk-reward ratios, to each his own. But the risk is far, far too great for me. I have had the benefit and pleasure of meeting many multi-millionaires and all of them created their,wealth buying and holding real estate. None made them flipping.
That being said, I do turn my properties from time to time. I buy or sell a property once every 5-10 years for various, well-founded reasons. But that is far different from flipping or timing a market.