If you’re a high skill laborer, jobs are replaceable, but your time and emotional well being are not. All of the “we’re a family all in this together, rah rah” stuff is absolute nonsense designed to convince you to ignore your own self interest for the sake of the company’s self interest. You should look out for your well being ahead of the company’s, because they will not look out for yours.
Also, you’ll never convince the board that the executive is bad. Not only do they have an immense incentive to justify their own choice, chances are that the narcissist is going to be much better at manipulating the board than you will be at persuading the board. By the time you can persuade the board that an executive is toxic, chances are the damage to the company is already done, and you’ve had to spend years of your life dealing with the fallout.