Innocent hustle with a side of opportunistic robbery?

I don't doubt most people doing this are just as you described wholesale to retail. But clearly this particular individual had an insidious ulterior motive.

Still, OP shouldn't have engaged in the first place. I don't even acknowledge people when they're selling candy and drinks in the train or on the street. Multiple times I've been hassled to buy more than I wanted. They see I have more cash on me and continue to hover. No, thanks.