I could exercise on my 40 lbs, 3 speed upright 1940s english roadster in jeans and a sweater for cred, but that doesn't sound fun at all. People who don't cycle (unlike me and you I guess) can't price cycle kit by eye so they'll see me in lycra and think that I'm some dentist when in fact my gear is all very reasonably priced, comfortable and appropriate to my level.
Also, it always bother me that people talk about 10,000$ bikes or whatever which is very far from reality, meanwhile they buy 45,000$ cars when 20,000$ cars exist and no one bats an eye.
My advice to them was that there are no slow bikes, just slow riders.
Sure, there are benefits to picking gear that works for you, but that's probably about 10% of it. The rest is your mind and body.