We have different ideas of success. My idea of a successful startup is not that it must reach unicorn status, but that it either has a successful exit where the founders and early employees comfortable enough that they can spend time on their next startup adventure; or that the company survives and continues to grow.
You place a lot of value in unicorns, but there are downsides to shooting to be a unicorn too. If you make it there you may be fabulously wealthy, but you'll have so much investment that most lose control of what they created and many succumb to bad investments that have so much dilution the cap table becomes upside down. Also most who aim for unicorn status ("I want to be rich!") fail. I'm ignoring bubbles, because if you have something that has no real contribution but rides/sparks a fad, then you can still get a lot of investment during a bubble - don't know if you could get to unicorn status though.
As for those companies not being capable of being platforms for hate speech: Minecraft obviously, Spotify is music so that should be a clear possibility, Telegram is messaging so that is also a possible. The ones that are financial apps are unlikely hate speech platforms, unless they allow comments or reviews.
