probably were a cinkciarz, corrupt PRL official, smuggler, gangster, and/or had people sending you USD's.
Yes, I always wondered where one of my neighbours got his Fiat Mirafiori car from. :):)
But you omitted some groups: e.g. my classmate`s parents were dentists and they bought a brand new Polonez in late 1970s. An owner of a car service near my house drove another Mirafiori. And so on.
Those used to be imported to the UK back in the 80s as a cheap alternative
Cheap but with rich equipment - e.,g it had a rev counter, not so obvious in compact cars then.