Honestly, use isn’t the point. It’s a hobby- something to think about that’s not work, or kids, or working on the house or car, or finances, or what I really think of my boss. And it’s safe and keeps me outta trouble. And as hobbies go, even with cabinets full of stuff, it’s cheaper.
Why do I have so much shave gear and why do I keep buying more? Because no one has told me to stop yet.
"Beware of the man with only one gun, he probably knows how to use it well!" With that said, also beware that this whole DE things somehow has a fun element that just gets you - tis what I've found anyway.
There's an art to collecting imo. To the op's question, why do people have more than one car?... or anything for that matter? Why not just 2 pair of dress shoes (brown/ black) and one pair of sneakers? Personally I enjoy the variety, the thrill of obtaining unobtainium items, and the knowledge that my collection is an investment, worth SIGNIFICANTLY more than I paid for it.