One thing Ive noticed, is that there's often an age gap, like between very early twenties (20-23) and the early thirties (roughly), where guys opt not to modify their cars. Its easy when you're young, living at home and having something big to prove, but when you hit your twenties most of us tend to have to think more reliable....for a while anyways
You have rents, utilities, cell phones and all those bills you picked up entering adulthood and you're not exactly living with mom and dad anymore...so those hard earned dollars sometimes have to go for more logical things
THEN, you have your kids and families and homes etc... I find that when many people go back to modifying their cars, its around the 40's+...the kids are older, the job is more secure and you have some play money in the bank...But even then I find that they're more apt to go for the stronger engine and generally more "expensive" vehicles over the smaller, rougher ones.
...But thats just what I'VE noticed
And you ARE only as old as you feel...(and look lol)