Earlier quoted context omitted.
Github didn't crowdfund $500,000 before having a paid tier and being profitable.
Fair point; I think I get what the OP was saying now. But, from what I understood, with the current crowdfunding scheme you're basically pre-ordering membership. NB: I'm not really sold on the product idea myself, just trying to understand the objections to the business model.
To me, the proposed project touches on a much bigger issue of how Twitter is a part of the internet infrastructure. Real time messaging has become really important, and there's some anxiety around how that infrastructure can be a part of the web in some trusted way.
Simply making Twitter community supported doesn't appear to me to be the best decision. We've learned about some great potential from Twitter, and I'm much more excited about something fully decentralized than I am interested in a community supported Twitter clone.