The next Superman movie might correctly conclude that you’re going to go see it anyway, so advertising it to the hypothetical you isn’t very valuable.

I could be wrong but I was under the impression that ads paid primarily per click, in which case surely the relevancy is important too?

Even if they pay per impression, pricing is ultimately driven by clicks.

Even if you pay-per-view of an ad, a company selling tampons will not pay as much for 1 thousand views of their ads on a youtube channel for construction workers, as on a youtube channel for girl's fashion. Because the former drives no clicks/revenue, and the latter does.

So yes relevance is extremely relevant to make money.

In many cases the buyer pays per impression.