I've only gotten two strikes in my life, 7-8yrs ago. And I feel like this was because my brother was downloading then recent, popular movies (which I almost never do). But before that, never did, without a VPN, and I used to pirate a lot more. Even further back, used to have a roommate who would go on movie and show torrenting sprees. We never got strikes. And that was when commercial VPNs weren't really a thing yet, but copyright strikes were well known. I've known others who've never gotten strikes either.

So I'd say no, not 100% necessary at all. But it's free or cheap enough to mitigate the risk. So that's why I use one when I do pirate, which is rare these days.