What do you mean? Can you describe what you mean with 'fascist rulership'? Then maybe I can try.
For example... people in Mexico many people suspect that politicians have associations with drug dealers, and many believe believe that particular bureaucratic systems (such as handing out public infrastructure projects) are exploited to distribute funds in ways that benefit those in power and their friends, these people I would classify as "conspiracy theorists", and in many cases they have been correct. You think that these people will always side with fascist rulership?
Isn't this a conspiracy theory? I think that the official position of the US is that they are not financing terrorists, and many of their military actions have been performed to defend citizens from their ruler's human rights violations. Isn't the Cuban embargo officially there to protect the Cubans against human rights violations? I think that arguing otherwise makes one a conspiracy theorist.
I am not saying this to argue, I am trying to explain what I understand with conspiracy theory - someone who is skeptical about the official narrative, and believes that those in power will not always be transparent and honest to the public.
I am aware of the "drain the swamp" rhetoric, that there was a QAnon, anti-vax, and other more fringe theories. But I think that this is a sub-set of conspiracy theorizing that is amplified by the media. Many conspiracy theorists are investigative journalists and critics of governments. And many conspiracy theories have ended up being true. I don't think that critical thought and skepticism is an exercise that only right-wingers should participate in.