I am a firm believer that you need a well-defined leadership role to deal with unexpected and non-linear side effects of people working together. You need someone to keep the threads untangled and forming a high-functioning web rather than a big snarl of a Gordian knot.
A milestone is less date and more definition.
A toxic person kills, and by kills I mean totally destroys teamwork.
You have no idea if your idea matters until you share it.
Managers tell you where you are, leaders tell you where you're going.
Criticism is the best sign you're onto something.