Point being that when people ask explanation seeking 'why' questions, they're not looking for a brute fact response because such a response really isn't an answer to the question. Same goes when asking "Why anything exists at all?" Answering with a factual statement like "It just does" or "It always has" isn't the sort of answer the question is looking for.
Anyway and to be clear, I'm not arguing for the existence of an unmoved mover. What I'm arguing is that if we think the question (Why does anything exist at all?) is valid and if we think the PSR applies to existence itself, the existence of an unmoved mover is the only acceptable answer since the other responses are no more valid to the sort of question being asked than my initial response to your questions.
