I think it's a sentimental thing more often than not. Some people definitely buy doubles, triples and even quadruples and wear their first pair (or first few pairs) into the ground until they reach lawn mowing monarchs status, and then there're others who simply love the shoe so much that they buy an extra pair (or pairs) knowing full well they may not get to wear them. There was a dude in the '20 Fire Red 5 thread who walked away with like 5 or 6 pairs. Of 5s. Shoes that we all know only have a 10-15 year life span depending on location and wear due to their midsole. Or the dude that had 4 or 5 pairs of '18 Concords and multiple '96 Concords. Personally, two pairs is enough. My humble sneaker collection is like a neutron star next to a red giant when compared to what a lot of people in here have and even then, I had/have double up pairs that I've not touched.