If you can't afford the hobby and have to steal the stuff, I think it is time to reconsider your hobby.
Well said!
Seems sensible right?
Unfortunately, the folks doing this are not sensible.
They actually think themselves quite clever because they pay for just ONE figure, and then they "cagily" return what they don't want so they can buy up what they do want with the refund.
They acquire a collection, and hence pursue a hobby for the cost of next to nothing.
And of course its wrong, and sooner or later they slip up and get caught.
( there's several legitimate ways to zero-cost a toy collection, and they take far less work and a LOT less guilt than swapping--but do these dummies ever think of that? Nope, that is why they are stupid crooks)