How do people use FHA loans to buy multiple properties??

[Dylan Lineberger]

I constantly hear people online (Social media) talking about getting an FHA loan and house hacking a 1-4 Unit property. They say to move out after one year, find a tenant for the unit you were in, and buy another property to rinse and repeat. My question is how they are getting the second property using an FHA loan?? Can't you only have 1 FHA loan at a time. I've read that there are exceptions like moving 100 miles away or jobs etc. Do they just build up enough equity to refinance into a conventional loan in 1 yr?