Putting expensive performance parts on old cars?

First off I've had an old 1997 Ford Explorer and put s ton of money into it just to get it in reliable running condition then put more money into it to get it to go even faster and still got my A kicked by a lot of newer stock cars. I now own a 2011 V6 Challenger w/ SuperSport Package. My question is this. Having now driven both new and old cars. Why do people pour tons of money into older cars to make them go faster and be more powerful when they're going to lose to a lot of stock newer cars. I have beat a ton of old 90s cars that I could tell have performance parts. My Challenger is nearly stock.
I even have a friend that poured $8000 into a 90s Ford Windstar (minivan) and its barely pushing 350BHP and I beat him every single time. I just don't get the hype anymore of putting a ton of money into old cars.

Most people have the sense not to waste $$ on old clunkers like you have + unless you are racing at a sanctioned track, there's no need for more HP in any vehicle

It's all about inadequacies in the trouser department. You might think you're better than your friends because you can buy an off the peg **** extension that's bigger than their custom ones. They think they're better than you because theirs is hand built and unique.