Mastodon.
Yes it gets harder, but it doesn't get 10x harder with 10x users. It should scale somewhat logarithmically. With millions of users that makes it still much cheaper to operate per user than with a thousand.
People tweeting stuff. We allow tweets from anyone.
RULES:
Yes it gets harder, but it doesn't get 10x harder with 10x users. It should scale somewhat logarithmically. With millions of users that makes it still much cheaper to operate per user than with a thousand.