Millennials were teenagers during peak cigarette campaigns but before vapes were readily available.

I look like shit but I did some very heavy drinking for a very long time. Finally on the back side of that. Hopefully in a few months I’ll be better off

Medicine has advanced

Nobody smokes anymore.

In addition to the smoking and decrease in alcohol consumption, I also think a ton of people are underestimating just how brutal the sun is on your skin and how much pushback there was against sun screen. It was viewed as a military product and the attitude from the 40s up until the 90s or so was basically that the more tan, the better.

A huge amount of people refused to use sunscreen, pretty much ever, until the late 80s/early 90s and then they'd go out and roast themselves.

Plastic surgery has gotten better if you're really only looking at celebrities. I know plenty of non-celebrity millennials that have aged like fine raw milk in a hot sun.

Are you in that age group? Your age group tends to look younger than expected, younger groups look like perpetual babies, and older generations look like perpetual adults/old timers. Always been a thing. Do you remember being 10 and thinking your 18 year old cousin was a full grown adult? When you're even just 25, you might think your other 18 year old cousin looks like a baby.

It's not just bodily appearance, it's their style. If I saw a 40 year old man with a combover and sideburns while wearing a short sleeve button down, I'd say they owned a house in 1976 on a used car salesman's salary. I'd have to cognitively recognize that even a 20 year old in 1976 would be 70 now. If I saw a 60 year old in an Arctic Monkeys shirt and cargo pants, I'd probably gauge them to have been a teen with an ipod. In reality, they'd have been 35 when the ipod was first released. There's so many cues we use to evaluate a person. Hair, makeup, clothing, accent, vernacular, interests, activities... Plus, it's not just association of trends to their calendar years, but association of trends to your age. The fang bangs pictured are more recently trending, but if you're ~35-45 now and she currently had whatever that post-goth emo fringe sideswipe blond/black fade style is called, you'd probably still take 10-15 years off your estimate. Meanwhile, take someone like Amy Winehouse. What do you gauge her age to be? Beehive hair, winged eyeliner, vintage sound. Not gonna /spoiler tag but she died when she was twenty seven.

I just watched Ghostbusters for the first time since I was a kid. Those dudes were like 30 ish. They looked like they were 45-50. I'm like 8 years older than most of them were at the time, and not to blow my own horn, but I think I and my friends look far better than they did at that age.

There's probably some survivorship bias going on here. You're not really going to see pictures of people who have been unattractive their whole lives, I wouldn't think.