They've also been around for a decade, and so similar to Harry Potter there are a lot of people that "grew up" or "matured" with those movies and so see those movies as being a large part of a long portion of their lives. Movies and TV shows have made a weird bizzarro world flip flop now that streaming services encourage binge watching of entire seasons of a show at once and the cinematic universe concept has made it so that movies can stretch on for a decade or more.
EDIT: I think that rose tinted glasses also play a huge part since if the good movies are really good you're more likely to remember the high points and gloss over the shit movies. If you have shit taste to begin with this get even easier to do.
Nostalgia is a very powerful thing because it goes right past logic and adds a sense of sentimentality to whatever you're getting nostalgic about due to all the attached memories. Personal example, but the film series that I grew up with and still love dearly even with its flaws is the Raimi Spider-man trilogy. Even if I 'grew up' along with Harry Potter I never felt the same level of attachment towards it even if I liked the films. Child me was peak consoomer because
everything had to Spider-man related and I rewatched that trilogy constantly to the annoyance of my parents (along with all the various Spider-man cartoons).
The thing though is that even with all my attachment to Spider-man as a character I have zero interest in lining up for any of the newer Spider-man films they've been pumping out, only exception was for Spiderverse because it was something
different. Even the new movie where they are clearly marketing towards nostalgia does nothing for me because I know they'll probably fuck it up somehow and not understand what made the original trilogy so good (plus Tom Holland just doesn't work as Spider-man for me). Unless they bring Raimi back to direct I can't see it working, but I just know the Marvel simps will still rave about how great the cameos are because they like anything Marvel puts out.
I rewatched the original Iron Man a while ago and lackluster villain aside, it's a solid movie in its own right. So they really started off on a strong note. One would have to wonder if it would've gotten as much initial momentum if it had been Thor or Cap whose movie was released first.
Marvel also revolutionized the "cinematic universe" by actually maintaining a remarkable sense of consistency and sticking to an overarching plot. Compare this to the X-men movies, which are only nominally set in the same continuity, with how many characters get completely thrown out and recast between movies and now utterly nonsensical the timeline is. And of course compare it to every contemporary attempt to kick off a cinematic universe that inevitably fails after the first movie.
When I still actually watched Marvel films I always found the worst films were the big assemble cast films they kept hyping up, one of the reasons I still have yet to see Endgame even if it's the 'end point' for the characters I did like. The self contained stories had more attempts at telling an interesting story.
I contend that the main reason the MCU succeeded is the promise of constantly leading to something bigger. That's why everyone makes such a big deal about the post-credits scenes - it's always about what's coming next, how this movie ties into the greater universe. So when Nick Fury showed up at the end of Iron Man talking about the "Avengers initiative", audiences were willing to sit through the mediocre but ultimately inoffensive Cap and Thor 1 to get to the real star of the show, Avengers (which for the record I think is a god-awful movie, but normies have shit taste so of course they eat it up).
As much as I agree that the original Iron Man is the better film, the first Cap film is what made me like Cap so much as a character and ultimately led to him being basically the only character who's story I cared about watching. While the last part of the film (excluding that final plane scene) was mediocre at best, the beginning half is just a solid film in my books that makes up for the lacking second half.
Everytime I look at this thread, I have to be glad I have only like 1 or 2 things I want but would be on my "to-do on the future" list instead of buying it immediately. Seeing people just buying something for the sake of it is very alien to me, like why die for a nonliving thing when you can wait a year or 2 to reconsider if its still worth it.
For most of my hobbies there isn't really a pressing need to get anything immediately as most things can always be picked up later. Where there is a lot a consoomer problems is in the realm of boutique bluray which thrive on FOMO and shiny limited packaging to get people to not think and just click buy. Most labels release standard editions after the fact, but they're usually physically bare bones or might be missing a couple extra features, which makes them a lot cheaper to collect. It's not a problem for say, Criterion films since they never really do limited editions, but it's pretty common with the other big names. Probably the biggest abuser of limited editions is Arrow films, especially recently with the 4k releases (which 4k in general just seems like consoomer realm scam full of annoying whining) of films they've already released. Take for example this redditor that has bought 3 copies of the exact same films with not much difference it the actual contents just to get the limited edition packaging and 4k release:
or you had people rushing to buy the 4k Dune release even while admitting they don't even like the film, but they needed to get it for the "beautiful packaging" that contains the film. Same thing was happening with the Shout Factory 4k Halloween releases that people where rushing to buy all of even if they only liked 1 or 2 of them. This isn't even getting into the shitshow that is slipcovers where some people get actually anger when someone mentions that they just toss all their slipcovers, get anger over corners dings that 'ruin' the cardboard cover, and buy films simply because the slipcover looks nice even if the actual film sucks or they already have it.