A mix of avira and malwarebytes locally, and virustotal if I’m especially sceptical.

IMHO whenever you actively need something and the owner either doesn’t make it available or the price is prohibitively expensive, it’s justified. That especially includes papers, books and other tuition material that’s been paywalled or made expensive as hell without any actual reason, even more so if the author gets next to no compensation.

Downloading series and movies that aren’t being streamed anymore, by all means.

When it comes to current movies, it depends on what’s available. Unfortunately most streaming platforms don’t have Chinese subtitles, and my wife often struggles to fully follow the original audio and the English subs often disappear too quickly.

For software, my personal stance is that if you use something every once in a while, pirate away. If you use it regularly and/or generate income from it, then pay your dues.