How are you making money if always in debt?

[David Ogas]

Hello Everyone:

At this point, I am a prospective investor who is looking to get into multifamily real estate. In short, I'm in the research phase of my development and in doing so, I've encountered several strategies for acquiring real estate and developing a portfolio.

Whether it be 20% down and then later, utilizing another 20% down to buy more properties, or by utilizing the BRRR method, the thing that I can't seem to understand is how anyone is profiting if they're constantly owing money to the bank, without paying off the mortgage in full from the first property?

On the surface, it appears that you're only making partial payments on one property, and then moving on to the next property by adding another mortgage that you're still responsible to pay for with interest. It would seem that if you're always in the red, that at some point, you could get yourself into a lot trouble with the bank or potentially ruin your credit.  

In short, what's the point that I'm missing?