In its filing with the SEC, Twitter reports that it has about 250 million active users.

But about 40 percent of those users never actually tweet; they just read other people’s tweets.

And perhaps the most telling number: people who signed up for Twitter and have since abandoned their accounts.

That number is about 650 million.

In other words, about three out of four people who sign up for Twitter eventually stop using it. And as time passes, that percentage may grow, because for some people the period before abandonment may be longer than it is for those 650 million.

And according to Business Insider, those number may be optimistic for Twitter…