I had an ad on Facebook marketplace for a synthesizer. The guy who bought it gave me his business card - cloud architect for a competitor. He didn't give it to me because we were in similar field - we had a pleasant conversation over shareEd hobby and he gave it to me then, after which I realized we were in same field, so clearly he gave them around a lot.

If I consider changing jobs, or if I need those very particular services he's getting a call :-).