Yeah I hear you. Although he held on to his Roadmaster even when he wasn't filthy rich. My wife gets more attached to our cars than me. I come from a mindset of always dreaming of what to get next, like a bimbo who hops from crush to crush - once the novelty wears off, time to move on.
I bought my 4Runner new in 05 and it's a uniquely useful car in that while I'm still getting distracted by other possibilities (more luxurious, larger, whatever), nothing would suit my needs for it better and it's mine... so unless it starts dying or I get filthy rich and can afford to buy a new nicer truck outright, it's staying (which probably means till death do us part).
My E30 started its existence with me out of a need to wrench on a car, and it's gone through so much with me and my wife, been so many places, cost so many emotions and dollars, that it's like the ultimate family heirloom. Plus I've dumped more money into it than I care to remember (the turbo engine alone has probably cost me an easy 15 grand), so at this point, beyond the emotional attachment which would veto anything anyway, it would simply make no economic sense to sell it - it would be barely more fiscally intelligent than setting it on fire.
My wife has a hard time letting go any of our cars. Well, with the E30 she flat out said no. She lets me do anything I want in life but this was pretty much the only time she's told me no (she didn't initially but when I changed my mind she told me she would have never let it happen...). But we've had other cars and she was so sad to see them go, I initially thought maybe this was her most favorite car on earth??? But then the next one is the same thing. I had a beater DA teg that she smacked into a guard rail on an icy ramp, and it cost me little, to buy or maintain, so I told the towtruck guy to keep it. She was very sad to let it go. I reminded her that it's a lame car with more dog hair embedded in the carpet than I have hair on my body, and she just said yeah but I'm going to miss it anyway. She currently has a Smart and while very excited to get the BRZ, every time we come home and she sees her Smart, it's like saying goodbye to a baby you can't keep... I still fall for it sometimes, asking if she really wants to keep it cause we can, and she says no it's alright.
So I think this is totally normal, and it's geometrically compounded by the fact that you do the work. I had an E34 M5 that I put tons of money into in university, it was the fastest naturally aspirated M5 I've ever seen (would drag with tuned E39 M5s dead even) and I was relieved to sell it to close to what I paid (forgetting all the other money spent). It was just money and a cool car. It wasn't effort and emotional investment. Leno mentions this in the movie - that if Bana had done the work on this stage like he had all along before, he wouldn't have hit the tree. Once someone else built the car, it became their car, not his. So his emotional investment and respect for it went away.
Was this the car you've done the most work on yourself?