Your percentage on 1965 dollars is way off, according to the Bureau of Labor and Statistics. Try over 700%. But you made a lot less then. But that's inflation; perhaps you are comparing media income. In 1965, media income was $6900. In today's dollars, that is $55,985 . Median income in 2019 was $63,688. So you actually have a LOWER media income in 1965...
As for paying off a mortgage early...who the hell is paying 7%? We haven't seen awful interest rates (baring poor credit) in a LONG time. Our house is financed at 3.25%. Could pay it off today, but investments tend to pay out more than that, ignoring any tax advantage.
As for new vs used, it simply comes down to tracking actual cost. I keep spreadsheets of all of our vehicles, with all maintenance and repair costs, along with updating what i'd expect to sell it for regularly. Once that monthly cost number after sale climbs to a certain threshold, it is time to sell. That's what triggered buying my truck, my last one (Escalade EXT) was hitting a number that was no longer making sense.