A lot of D owners just don't drive them. To hard to fix them if something breaks, maybe? I don't know. Don't have much use for a car I can't drive.
Yup, that's been my experience too. I ALWAYS hear of someone who has one in their garage but never drives it. An ex-GF had a neighbor who had one that just sat, half taken apart, under a car cover in their garage. She told them I'd be more than happy to look it over and give them some help in getting it together and roadworthy, but they were content to just have it sitting there.
Parts aren't a problem- 99% of the parts on the car, I can have a replacement (usually New Old Stock, but for common wear items they still have them made) at my door in 24 hours if I'm willing to pay for overnight shipping. Finding a shop that you trust to work on one if you don't live near one of the official DMC shops though can be a challenge- but I've long been of the mind that you shouldn't own a classic car if you're not capable of doing at least a majority of the work to maintain it mechanically yourself, so I do all the work on mine myself outside of things like swapping tires. The K-Jet system can be a pain when something goes wrong, which is a large part of why I (and many of the others who have done so as well) converted it over to a carb which, while still not perfect, is a LOT simpler and has more people and resources available to work on than the K-Jet.
When I first bought it mine wasn't running and needed a lot of work, and I got asked ALL the time when people heard about it, "What are you going to do with it when you're done?" to which I'd usually look at them like they'd grown a third eye and answer, "Drive it." Right now it's my main car (though as I noted I ride my bike way more than driving at the moment) since my usual daily driver, the Saturn, has some issues I need to resolve before it can be safely driven. It has its quirks- I've never managed to track down the bad ground that means even with the battery cut-off switch that I'll have to have the battery charged back up every other month or so- but otherwise it's a great car to drive around.