It might feel that way, but I promise you it's definitely not "everyone".
Hell, it's only about 45 million in the US (assuming you believe Twitter's own numbers - which I definitely do not).
So at best, you're getting 1 in ~8 folks in the US. More realistically, I'd assume your audience is more likely 1 in ~20 in the US - assuming you manage to get literally everyone to follow you.
Is that larger than you're going to get on your own site? Probably.
Is that everyone? fuck no. It's basically no one. You're reaching the worst 5% of the country - those who have nothing better to do than browse twitter, or those who are using twitter to promote themselves.