We've all met them. People completely fail to comprehend how anyone could hold a contrary opinion to theirs.
Religious fundamentalists who are so convinced that their answer is the "one true answer" that they are dumbstruck by people who recalcitrantly insist on paving their own way to hell
Long-established co-workers who know that the way things have been done until now is absolutely the best possible way to do them, and that any other approach is inconceivable
They don't simply disagree with you, they completely fail to see how you could possibly disagree with them.
And it's not just the big things, the important things - if something is worth saying, for an incredulous dictator, it's worth proclaiming
Example: You serve a meal, and your guest doesn't care for the avocado in the salad - the only person present who doesn't. Do they just put it on one side? Do they say "I'm sorry, I don't like avocado?" No. Instead, they glare around the table and loudly declare "I don't understand how anyone could like avocado, it's so slimy and bland."
This happens with everything. They are at a loss as to how anyone could prefer rock music to classical, or opera to slash metal. They know that reasonable people would only ever dream of buying their groceries from the supermarket that they themselves choose. And, obviously, anyone who spends money on something they deem unnecessary is simply wasting it.
They will invariably tell you so, as well, because it's equally incomprehensible to them that you might not want their opinion.
It is impossible to argue with an incredulous dictator, not because they won't admit they are wrong (although they won't), but because they won't acknowledge that an alternative opinion even exists. Your only choices are to behave passively and go along with them, or to act in a passive-aggressive way, and pretend to agree, while ignoring them totally. Forget your assertiveness skills, your communication training. Just nod, smile, and get out of there. Fast
dedicated to my mother-in-law, who has the sole saving grace of having given birth to a wonderful son, and my ex-boss, who has no saving graces, which is why he's an ex.