I would think that most of us grew up in the '50s, '60s or '70s. I'm talking being teenagers and in our 20s. Back then, it was almost sacrilegious to be seen in a 100% stock muscle car.
"Stock" meant slow, compared to the cool street cruisers/racers that I grew up seeing on Van Nuys Bl, etc, in SoCal. Or at the local drags, on "run what you brung" nights.
I'm taking about street-driven, daily drivers, not pro race cars. Most of us only had one car. And we were just regular young guys out looking for everything that young guys seek.
"Stock" cars in my day were either Day One brand new (that's ok), or your sister's car (not cool) or perhaps your mom's car (definitely not cool.)
By age 30, most of the muscle car owners guys had aged out, gotten married, had kids, and weren't the ones out there street racing any more. Their muscle cars went on to their second and third owners (more teenagers and/or 20-somethings) who modified them even more.
Turn the clock ahead the 50+ years to today, and we're mostly old-ish guys. Some of us owned muscle cars back in the day, but many didn't. That's ok too.
I'm a Day Two guy, and always have been. Stripes, mags, fat rear tires, Hurst shifters, headers, giant carbs, built engines, transplanted engines (427!) all the stuff. We cruised and raced and tore our stuff up doing so, then fixed and improved it the next week. Always seeking better, faster, cooler. That was the era.
Today, I'm a bit more enlightened, and even like and respect the guys who go the to extremes to have a perfect concours car.
Peel out...