This is another reason why a lack of transparency with user votes is bad.
As to why it is seemingly done randomly in reddit, it is to decrease your global karma score to make you less influential and to discourage you from making new comments. You probably pissed off someone's troll farm in what they considered an influential subreddit. It might also interest you that reddit was explicitly named as part of a Russian influence effort here: https://www.justice.gov/opa/media/1366201/dl - maybe some day we will see something similar for other obvious troll farms operating in Reddit.
It's ok, you only need to question the information you disagree with as made up, everything you want to hear is obviously implicitly true. Kudos on asking for evidence while saying you don't really care for it in the same sentence.
It's true, I've now changed my resumé to that of a cat veterinarian. Some people might say extraordinary claims need extraordinary proof, but you've really touched on the reality of it, that extraordinary claims, well, you are just pulling your criticism out of Google search and absurd common knowledge you might have been taught in biology class, clearly you consider yourself knowledgeable far beyond your means.