I don't think either were ever said by competently literate people (wtf is "irregardless"? And do they mean they could "care less" about a subject or do they mean the opposite but don't understand negation?) so idk if this fits what OP was saying entirely. They're just obvious mistakes that have been normalized as people got dumber, right?

I find intensifying to be more natural than negating for things like “I couldn’t care less,” or “irregardless,” or “misunderestimate” to a certain extent — if something is “worthwhile regardless,” I don’t have to regard that, but if it is “worthwhile irregardless,” I really don’t have to think about it at all. It just seems right that if I put a bunch of negative words in one sentence, it should be really, really negative, instead of it being negative if I used an odd number and positive if I used an even number; same with prefixes and suffixes. I think it’s probably too much to try to reform English to work as such, but if I were building a conlang it’s what I would do.

I could care less