Lots of people optimise because they fell in the rabbit hole of optimisation and it became an addiction. Like in every hobbies some people completely lose touch with reality. I've seen videos of people comparing weight of bicycle seats and how to shave like 13 grams of weight of the bike, meanwhile the dude had a dad bod and shaving his torso would have shaved more weight than his $$$ seat

There is riding fast and there is riding fast but just a tiny bit slower.

I have a modern race bike, less than 3y old with some but not all of the latest aero features. I also still own my 30y old racing bike that I used to race until 20years ago (it was already old bike then). It stays at my parents place and I ride it maybe twice a year. If you ask any bike reviewer he will tell that old bike is obsolete, feel much slower and make me lose 45s over the course of a 50km ride according to the data given by the manufacturer. If you ask me, sure I feel a difference, mostly in feeling, when I start riding the bike. But after 5 minutes all this is forgotten and I enjoy the ride as much as on my more modern bike. And that bike is perfectly fine surrounded by superbikes in a group ride. Actually I did one this summer with a group that tend to stay together but ride at a fast steady pace until the last 20k where the wait "policy" disappear and people start to attack the climbs at max pace. I ended up in the 5 rider leading group out of maybe 40 and I was totally out of shape.

That old bike would sell for 300-400€ in the second hand market right now. The difference with a 2k and 8k modern bike is much lower.

Don't get me wrong, I also love to go down a forest path at 45 kph to the point where I get scared, but I know that I also have to go up again. But going as fast as possible on a horizontal path is not attractive to me at all. If I want to expend energy, I prefer to ride up a hill where I then can have the fun of riding down, even if I have to pedal 20 minutes up to then go down within a minute or two.

But I also recognize that there are those who are already super efficient and want to get the absolutely most out of their gear, even improving it as much as possible, which is really ok by me. I wish I were at that point, but I think I'd first have to go to the gym for that.