Yup. Its a little like being a landlord (which is probably your example, I didn't see it).
There's statistics depending on the city, where renting out a place is always 10-15% profit over the expenses of owning and maintaining a property. Also, if you go to a bank with a reasonable income and buy a property that already has a tenant, getting financing is reasonably easy.
That basically means that theoretically, over a reasonable period of time, you could buy an infinite amount of small properties, use the money from one to fund the next, quickly make enough to hire a super to maintain the properties for you, and basically have free, infinite income.
But the world doesn't work that way, does it? Anything easy is a race to zero. Yet there's still a 10-15% profit on being a landlord (not even counting the property value going up by the time you sell) Why?
Oh right, the "work" here is the risk taking. You could be getting a tenant that doesn't pay and be stuck trying to evict them (extremely hard in some states) and foreclose on the spot. A street gang could open up shop next door and the police has trouble getting them out and your neighborhood goes to hell. A contractor could get a permit to build a high-rise across the the street. City taxes could go up faster than rent does.
And thus, I know a lot of people who tried to become landlords and ended up in financial trouble. That risk is what you accept to get an easy real estate profit.
This is the same thing. Medallions were easy profit because not everyone thought so, else they'd have been a race to zero too. And thus, the risk manifested itself.