Tor: "Darkweb" stigma. Often used by criminals, thus periodically reported about in a distorted manner about how it is only used for crimes. The fact it resists censorship is not mentioned, conveniently.
Bitcoin: "cryptobros" stigma. Often associated with ransomware, price hikes for regular consumers (yes, I know this was basically Etherium-miners' fault, but does the general public care? To them it's the same thing!) and seen more as "play money" than real money. Bitcoin stores are far inbetween - but I recently saw some sick looking PoS terminals and such that make payments with Bitcoin seem as "normal" as anything else. They were lightning-based, IIRC.
Nostr: I onboarded two users and ran into different issues both times. The only thing that was consistent between the two was them asking: "Who do I follow" - and "Why is this not working, I did use an extension with my nsec". There are a lot of edges to be worked on because it's still a young protocol and platform alltogether. It is, however, already much more capable of a "superapp" than Twitter will ever be, may Elon try as he might, lol. And, the fact that Nostr can be more than just microblogging is also relatively unknown. There are marketplaces in the NIP specs, but I haven't seen a good implementation of it yet.
I love all three of those things, especially the third, followed by the first. In fact, I would even like to add i2p into this mix! But the reality is that unlike "established" methods (clearnet, fiat), we haven't reached the same convenience factor yet and still require a good amount of know-how to get people to use it. The best thing in this regard is Orbot on Android - it's genuely amazing and super easy to use! Not entirely K.I.S.S., but damn close.
And this is why I am still here. This stuff... rules. <3