On a more practical level, I would probably go on PreP if I regularly had hookups with men. I’m actually somewhat envious of the gay scene in that regard. The option just doesn’t meaningfully exist at the mostly-hetero sex parties I’ve been at.
I mean I'd worry that they were being honest, but mistaken. I'd have to do a lot of research on the efficacy and frequency of testing beforehand (e.g. it's possible that it might be calibrated to be frequent enough to provide proper care for the patient, but not to guarantee to protect partners).
So really you need to be trusting that they are responsible enough to take their drugs every day. These days that is pretty easy, most people take 1 pill in the morning and that's it.
The fact that people don't trust it means nobody's casually taking it or taking for granted that other people are taking it. So it increases awareness of the potential for contracting HIV and underlines the need for protection. At the same time, you can independently choose to take it and provide yourself more protection. So I think it all balances out.