My 2015 Focus ST3 has only 33,600 miles on it. By the OP's definition, maybe I keep it "locked up". I think a broad judgement that I'm missing opportunities to enjoy my car lacks nuance. For example...
(1) The job at which I've been employed since June 2018 has no office. Every single person in the company, from the founder and CEO, to the newest junior customer support rep, works anywhere they want. I often go two to five days at a time without leaving my house. If I don't have anywhere to drive, then my ST won't accumulate any miles. Neither will any other car. My ST is my daily driver in spring, summer, and fall but I just don't drive as much as I used to.
(2) I don't drive my ST in the winter. Ever. I've never purchased winter tires for it, nor a spare set of wheels on which to mount the winter tires.
I purchased my ST at age 44, and it's the first new car I ever bought. It is *by far* the quickest and nicest car I've ever owned. In central Ohio, two things are applied to the road to address snow and ice: salt, which is somewhat corrosive, and a brine solution, which is fantastically corrosive. I've been fixing cars since 1994, so I'm accustomed to working on rusty vehicles, and I want my ST to be free of that corrosion for a while. I love taking my wheels off to rotate my tires, or clean the wheels, and seeing no corrosion at all even after four years. I love getting under the car to change the oil and seeing a pristine chassis. My ST has *never* seen salt or brine. This please me; it's part of how I enjoy the car.
The car I drive in the winter is a 2003 Ford Focus ZX5 which I've owned for 10.5 years. It's old, noisy, and rusty. It's also far less enjoyable to drive than the ST. But if the point here is "You should be enjoying your car" then the details of enjoyment matter a lot. In the winter, I'd have winter tires on the ST. This is nearly a contradiction: winter tires on an ST. The ST is a marvelous corner carver: nearly instantaneous turn in, video-game steering speed, hand-of-god brakes, good mid-range punch from the engine, and trailing throttle oversteer which, combined with big sticky tires, make the ST a giggle and whooping machine. Put winter tires on it, and it does none of this very well. I don't see how that's very enjoyable. I'd rather drive my rusty rattletrap whose fun in the snow is that I really don't care so much if it gets exposed to salt because it's already visibly rusty. Even if the rattletrap gets damaged - it's worth almost nothing.
(3) Cars are tools. I have a rental house about 4.5 miles from my house. I'm often over there to do maintenance or fix something, or to fulfill my contractual duty as trash collector. I never drive the ST there. Why would I? I've got tools in the back, or even trash. I drive the ZX5.
There are also different types and levels of enjoyment. Next weekend, I and four friends will converge on Robbinsville, NC for 2.5 days of taming the Tail of the Dragon. For the uninitiated, this is a famous road comprised of 318 turns in 11 miles. Last year we ran TotD 8.5 times out and back. I'm sure we'll do that and maybe more this upcoming trip, plus a lot of other twisty roads in that area. Last year we did about 10,000 turns in three days, and at least half of those were closer to the limits of the tires than not. The ST positively shines on a road like this, and my tires are visibly worn at the end of the trip. Maybe WHAT you do with the miles matters as much or more than how many miles.