I've been in the company of really smart (and likable!) Heretics and they tend to go out not with a bang but with a whimper. It's sad to watch. They may be even be right but their persistent negativity and challenging of the status quo (even in minor matters) ends up wearing people down. Then eyes start rolling when they talk and their rants are met with sighs rather than attention or acknowledgment. Then they start…
At this point it's the management fault for not doing (having done) something about it. Firing the person, fixing the status quo or maybe empowering them to fix it.
And yeah, I'm aware I might now sound like the Heretic themselves :)