New 4 plex paid off in 7 years?

[Richard Miller]

It’s been a few years since I have seen this subject discussed so here goes. I am contemplating building a 4,200 square foot 4 plex on a $50,000 piece of property in North Texas. If I can build it for $75 a square foot that would be a total cost of $365K with $130k (25% down + property) out of pocket. Rent would be minimum of $750 or $3000 a month. It would appear I would have the note paid off in 7.2 years and the full $365k paid back in 9.7 years just in time for my retirement. I then have a free and clear 4 plex that is fairly new. I know this is a quick and rough description but I need to know what I'm missing in this idea.

Thanks Rich