"Real Estate Isn’t a Cash Flow Business"

[Carlos Zamora Jr]

This is my first time posting here, and I am sort of new to real estate, so if I do make any mistakes, please feel free to correct me. 

I am currently reading Timing the Real Estate Market by Craig Hall, and have stumbled upon a statement that made me question whether I should be spending my time reading and researching topics about the real estate business; the statement is, "Real Estate isn’t a Cash Flow Business”. It stood out to me because Cash Flow was the main reason why I became interested in real estate. It states that the reason why “Real Estate Isn’t a Cash Flow Business” is mainly due to buyers  underestimating expenses & capital expenditures, which affects the cash flow projections of a property. How true are these statements? It also states that "the real money is made when you sell”. 

Thank you for reading!