Speedos were never particularly big in the US, so I can’t particularly comment on those.

I will say, that in 2022 I don’t think it’s necessarily shyness. We are now generally much more aware of the harms of UV damage to skin than we were in the 60s and 70s, and so there is actually a trend away from tanning and towards covering up. Which is probably for the best since skin cancer is the most common cancer in the US.

I'm not sure if awareness of the dangers of UV damage serves an explanation. The area covered isn't huge and tights aren't typical regions for skin cancer. Having said that, the heightened awareness may introduce a cultural bias…

I guess speaking of cultural bias, one other thing to note is that Europe and the US are not the only game in town anymore.

Japan and Korea, and probably in the future China, are big players in cosmetics and fashion these days, and those countries never had a big nudist culture and generally dislike tanning and nudity even more so. And their products are gaining ever greater market share in the West.

Of course. I was writing mostly from a European perspective.

Right, but even young European influencers today are often hawking Japanese and Korean cosmetics.

Our cultures are mixing together in this globalized world, and other stuff like K-pop is already big business in Europe.

My recollection is that Speedos weren't exactly rare but they tended to be more associated with sports than something you wore to hang out at the beach.

There may be cultural differences (esp. regarding the US, which were generally known as somewhat prudish in these concerns), but in Europe sporty swimwear (rather by Adidas and similar domestic brands than real Speedos) was the default. Anything else was asking for an explanation or would even provoke open ridicule (like Hawaiian shorts).

That is almost certainly fair. I know I wore Speedo-like swimwear for water polo but would have worn nylon shorts of some sort at the beach generally.

Speedos are associated with older generations and/or homosexual themes. That is why they are not popular among young males. Nothing to do with shyness.

I don't know. I think some young males might not be sort of shy when it comes to punishment size. There's no shortage of posts on the internet or media stereotypes about size. And of course porn has a size bias too. It seems that some women want their man to stay private because they want the social approval of their friends group, which tends to place value on large members.

Obviously this doesn't apply to everyone, but I do think it's a non trivial number. Maybe it's a vicious cycle and more exposure of normal sizes would help normalize expectations/views.