Hands down the CEO. He may have great ideas but he is completely clueless on how to effectively manage people. I have watched him go through over 7 managers & senior managers in less than 2 years. He does not trust the people that work for him to do the job they were hired to do. He refuses pay anyone close to a livable wage that is below the management level and often tries to cheat his lower level employees out of their bonuses and reviews by constantly changing the goals last minute.
His expectations are not aligned in reality and unfortunately most of the people who work under him are to afraid to speak up out of fear of retribution (each person who has is no longer at the company).
If you have the misfortune of actually having to be in a call or meeting with him good luck getting more than 2-3 words in. He will cut you off and talk over you constantly, often talking at you and not with you which is interesting since two of his companies cultural tenants is transparency and feedback yet he will listen to neither.
Overall, he is the sole reason that I think after 12 years this company still considers themselves a start-up because he can't get out of his own way. Sadly, he will continue to lose good people because he refuses to pay them what they are worth (even after bragging in town halls that the company is making record profits) and does not care for the mental health or well-being of his staff.