People normally buy used because they have been trained that for most cars, buying a lightly used car is the "best deal" because the first owner already ate all the depreciation.
I am still having a hard time (frankly), wrapping my head around the OP of this thread posting a thread that basically is complaining that their 2 year old car did not immediately sell, when they priced it like 6k below a new one (not counting any new car rebates etc that someone might get).
In the case of used tesla model 3s, and buying used, anyone who can afford to pay 45k for a used one can also afford to pay 52k for a new one. Especially if financing it, because new car financing is almost always a lower interest rate than a used vehicle, so the payment on both cars is going to be similar.
I have bought used cars before of course, but in the case of model 3s, just because the delta between new and used is "fairly small" relatively speaking. The flip side of that is, its not likely to have a bunch of engine issues with a model 3, so higher mileage for THAT shouldnt be a huge deal for most.
There are likely to be smaller things, just like any other used vehicle. It should be cheaper to keep a tesla running for a long period than it would be to keep, say, a BMW / Audi / Mercedes. It may not be much cheaper than keeping your typical toyota / honda running however, as most people who own ICE versions of those cars drive them into the ground, and they are not that expensive to fix.
I dont think there is anything at all wrong with buying a used model 3, I am not saying that. I am just saying that the delta between new and used is relatively small, and anyone who can afford to spend 45k for a used one can also afford to spend 52k for a new one even if they dont want to.