Say more please.
tl;dr While it can have undesirable side effects, these are long-term. But these side effects make it a powerful nocebo for some people to the point where they almost instantly get side effects (nausea, anxiety, sexual dysfunction), despite that being pharmacologically improbable.
I started dutasteride when I was 20 and have been on it for many years and it really stops hair loss, because my hair loss was very fast and aggressive.
Again, I've heard at least 5 of these first-hand, which is kind of wild for a drug I've probably only talked to 20 people about in total.
We're terrible at detecting changes over long periods of time. If anything I'd think long term users would be much more liable to bias.