You can literally make your own twitter any time you want. My charitable view is that people are actually complaining about a monopoly on attention. It's an interesting subject but doesn't have anything to do with speech.
Until cloud companies decide to stop hosting you and registrars refuse to register your domain.
But of course you can also make your own cloud company and your own domain registrar as well.
Until your upstream network provider decides to drop you (this happened to Epik, temporarily killing the whole company until they dropped 8chan).
But of course you could also make your own backbone ISP.
It's not a problem even most garden variety racist assholes on the internet are likely to have, though.
Also, 8chan is doing fine.