Duplex to 4-plex to apartment building.

[Nicholas M.]

I was curious if this was a thing where a person buys a duplex, does a lil upgrading on it, lets it appreciate for a year or two and then sells it for a profit. Then the person does a 10-31 exchange and rolls the profits into a  4-plex, does a lil upgrading, lets it appreciate for a year or two then sells it for an even bigger profit. then the person just keeps doing that ad infinitum. Does anybody at bigger pockets have any experience doing this? I have a duplex and want to acquire 20 units or more as my goal but saving money and buying more multi-families outright is taking too long cause I just cant save enough. Zillow estimates my house duplex at $256,000 right now which is up $37,000 from the $219,000 I bought it at last year. I could easily use that money plus my savings for the down payment and upgrade to a 4 plex or even a 6 plex. Any thoughts on this? Thank you