I would watch the movie adaptation of a book I enjoyed, or vice versa, but I wouldn't read a book in translation that I'd already read in the original, and I don't think many people would. (I might read the original after the translation).

So in some sense a translation is less of a unique work than a film adaptation.

Classical scholars are an exception here, who might read Homer in half a dozen translations. But that's for two reasons: firstly, classical scholars are likely translators themselves, or at least students of the art of translation; secondly, there are only so many great Ancient Greek texts to read in the original.

To each their own. I've read books in my second language that were translations of English books I'd already read. To be fair, that had been mostly pedagogical. I've also read multiple translations of the Illiad, for example, and don't know any ancient Greek. I've also read modernizations of Shakespeare.

Art is a complex thing, and doesn't really respect the commodity form. The same "work" can be totally different to people with different experiences, skills, neuroses, etc. You can read the same book twice and enjoy it, or not, differently each time. People enjoy live music exactly because each performance is different. Ultimately we're all trying to wring meaning from our lives, and art is a tool to give you some leverage in that work.