I feel the same way about these sorts of terms — for me, it’s especially strong with ‘philosopher.’
There is a small set of terms that are just used to gain credibility without actually having accomplished anything.

There is something to be said for the person who writes about philosophy of knowledge, for instance — this person is engaging in a conversation that has been established as pertaining to philosophy, I think this person may have a right to call himself a philosopher. But the run of the mill Jane Doe who’s watched a few School of Life videos and TED talks and in general thinks — what does this person calling themself a philosopher add to the conversation?

Watching a bunch of videos and learning a bunch of stuff in different fields does not a polymath make.
Da Vinci is called a polymath not because he knew a lot about a lot — it’s because he was actively making contributions to furthering the knowledge in all of those fields which he knew about. He made contributions to painting, sculpting, music, cartography, biography, anatomy and so many more fields — that’s what makes him a polymath. He’s not a polymath because he could tell you about the Vitruvian man and the Mona Lisa — he actually made those.