Is it you? Considering that the pattern repeats, the answer is probably "yes". You're having a hard time transitioning from being The New Hotness to Just Another Worker. Your ego gets bruised, you make a bigger deal about your opinion than it warrants, and you burn a bridge or two.

You're not doing it on purpose, but the fact that you're asking about it shows humility, which is a good thing. Always be in a position of service for people. Try to be less ego driven, and more service driven.

And don't give up!