As someone who declare as dinosour and being new to all this, I don't agree. The best way to make it mainstream is to render complex tech concepts into relatable language so dumbass like me and millions of people can understand it. If you hit us first with terms like "public key", "sats", "zapping", etc we will run away because we have no idea what the heck is that. What we do understand is:
1. True freedom of speech, no censorship, independence
2. Possibility to create amazing things and spread powerful ideas without being a victim of algorithm
3. While in traditional social media you are invisible, shut down, shadowbanned...here you can be equal and visible and effortlesly be awarded and earn money just because others appreciate what you have to say/share/express. It's entirely different, refreshing experience!

I could go on and on...but you get the idea. Basically adressing pain points of current world,internet and social media and in simple language offering solution - nostr. explaining all possibilities it offers (again in regular human language). Also, I would personally promote it as a place that is not ego centric, but focused on service to all. I would also promote post and ideas of this kind.

Maybe the most important part is arranging free education "what is #nostr and how to set it up" in high schools, universities and independent events organized by nostr itself. This should be done all over the world physically, not virtually. The fear of new and unknown needs to be overcome, and having real people next to you who can guide you, and show you and answer the questions is crucial!

At the end of the day, nostr should be presented as powerful movement since realisticly maybe for the first time in thousand of years allows people and nations who were opressed, robbed and poor get their dignity and freedom back.