Indeed, just because one dellusionally believes they are presecuted, does not mean they are. People have been memeing and satirizing leftist about this for decades at this rate, "oppression Olympics" and such. More recently, "Rugged. Vegan. Compassionate. Victim": https://m.youtube.com/watch?v=arw1pcqLI_M
The point of the clip/episode is you should "brand" yourself as a "victim" (even though you're not) because it's in vogue and perceived as "cool." For leftist, it's virtuous to be a "victim", so people pretend they're being persecuted or victimized to gain clout.
How is one pretending to possess a quality that is viewed by society at a given place in time as being "virtuous" related to someone suffering from a delusion that they're being persecuted and also related to someone actually experiencing persecution?
Furthermore, I am still confused how you can conclude it's tied to a particular area on the political spectrum.
To be clear, if there's evidence of someone is being persecuted then that is it likely real while in the absence of evidence it is likely that they are suffering from a delusion.