Where people have erred is in thinking, "If we were going to legalize pedophilic behavior, we would start a grassroots campaign like NAMBLA's."
Nah, that's not how it's done. In 2020, when the most relevant media outlets and tech companies are controlled by a small oligarchy, the way to create change is from the top down; get the establishment on board, and have them create a narrative favorable to your side, and silence (and if necessary, crush) anyone who gets in your way.
So for example, if we were going to legalize pedo behavior, we would first get organizations like the SPLC and ADL on board. Get them to say that anti-pedo sentiment is antisemitic or something, because of a lot of Jews like Epstein and Weinstein getting busted.
Next, you would want to get the major media outlets saying 24/7 how wrong it is that pedo behavior is banned, and what a human toll there is, and how this intersectionally affects a bunch of other affected groups like gays, etc. So now, if you're anti-pedo, you're not only antisemitic, you're also homophobic. We could probably find some way to tie in women's rights, too (e.g. by saying female teachers like having sex with 13-year-old boys), so that those who oppose pedo behavior are also misogynistic.
Once the media establishment became favorable to this turn of events, one could then get a bunch of academics to put forth research that's probably been languishing in file cabinets, supporting the premise that pedo behavior isn't harmful to children. Organizations like the academies of pediatrics could get on board safely at that point, lending the idea more credibility, and their statements could then be cited in courts.
The next step would be to deplatform the enemy. Anyone who says that pedophilic behavior is bad would be kicked off of YouTube, Wikipedia, Twitter, Reddit, and every other mainstream website. Anti-pedo subreddits would be banned for hate speech, and anti-pedo books would be removed from Amazon for the same reason. A lot of anti-pedo content would simply disappear from the Internet and not be available outside the Internet Archive (or maybe it could even be reported and removed from there too). It would also be taken off the bookshelves of reputable libraries, as people complained they didn't want their tax dollars going to support that trash.
Next, major corporations would run promotional campaigns saying how they celebrate pedophilia. Once momentum behind this started to build, they would all get behind it, and everyone would rush to participate in the virtue signaling, with their colorful profile pic filters and whatnot.
Maybe there would be some sympathetic person who would become a martyr for getting attacked, maybe even killed, or bullied to commit suicide, just for being pedo, kinda like what happened to Tyler Clementi. The facts of the case, or his actual background, would be unimportant; those could all be elided away in the news accounts as long as there was one picture of him that looked good (kinda like the graduation photo of George Floyd).
At that point, anyone opposing pedophilia would seem basically like a murderer. It could be argued to the Supreme Court that the equal protection of the law was being denied to pedophiles, and that their civil rights were being violated. With the backing of the media, the High Court would feel safe making a ruling that the Constitution and federal laws demand pedophiles be given protection, and allowed to openly engage in pedophilic relationships, without being discriminated against by employers, cake shops, etc.
This ruling would not provoke a constitutional crisis, as long as there was at least some minority, like 40% of Congress maybe, willing to go along with this idea. They'll renounce their past anti-pedo statements, if they feel like that's what they need to do to keep the media or other powerful interests from opposing their next electoral bid.
The fact that this country so quickly went from passing constitutional amendments against gay marriage, to supporting a Supreme Court decision making it constitutionally mandated to offer gay marriage, shows how fast stuff can change once the establishment gets on board and starts propagandizing a certain way. Public opinion is pretty malleable; it just takes maybe five years or decade to totally alter people's views and make public policy do a 180.
With control of the public opinion and therefore the country's politics concentrated in the hands of so few, and such a strong ability present by which any dissidents can be ruthlessly, effectively, and thoroughly suppressed, there's a great opportunity in front of us.
Imagine, someday the anti-pedo side might be relegated to just a low-traffic 1990s-style message board like this one that's down half the time. They'll have to reassure one another, "You're not alone in opposing pedophilia" but most people will not even be aware they exist.
If kids read about them in the history books, it'll be in the same chapters that talk about other injustices like slavery, or women being denied the right to vote, etc. Anyone who opposes pedophilia will just be looked at as a backward hick.
The only problem with this whole plan I've described is that the system that creates such a potential is also unsustainable and destined for collapse, so even if we did legalize pedophilic behavior, that would only last for the period of time before this whole civilization crumbled to the ground.
But hey, this society still has so much momentum behind it that who knows, it might be 100 years before that happens, so we could have a good run in the meantime.