Also, car maintence costs have exceeded inflation over time: https://www.officialdata.org/Motor-vehicle-maintenance-and-r...
As you experienced, spending $500 to keep a $1500 car from becoming a brick is a great value.
If/when I have the time, my plan is to take cars like this and part them out. Lots of people out there willing to pay for a working OEM part to de-Brick their car.
If you’re patient enough; selling rims one by one would pay off. Nobody really wants to replace all 4 when they really needed one.
Let's say a transmission replacement costs $1000 for your car (that's low, by the way). You could sell your car now for $1500 and buy a another one, or you can spend $1000 keeping it on the road for a few more years, sell it for less than it is worth now, and then buy another one. That $1000 was wasted since you had to buy another car anyway -- you would have saved that $1000 if you bought the replacement car sooner.
That only works if you can see into the future and know that you will need transmission work soon, and then it requires you to find a buyer who doesn't share that opinion. Essentially, you have to screw someone over.
Otherwise, if the transmission is already broken, the situation is that you either pay $1000 and get a working car (ie. repair the transmission) or sell your car for $500 and then buy a new one.
My bigger worry is if I get into an accident, the value of the car is so low that the insurance will total it, and now I'm stuck with buying a new car.