Not including the different paint versions, why do you buy them?
Are they for possible investment?
Are they for the sake of collecting?
Are they because you can't think of any other way to spend money?
For myself, I buy multiples of my toys for very few reasons:
They are cheap (on super sale clearance) and I keep them to resell or trade later.
I will use them in groups. This is primarily my 1/6 figures that I kit bash into a crew for a vehicle making slight changes on each one.
In other markets (Dragon, DID, Sideshow) I will buy multiples of limited production items at list price or higher, to keep for myself or resell in the future. This depends on what I have in my wallet to spend on birthdays, other gift occasions, home repairs or nowadays a tank of gasoline.

How about youzze?

TTT