Most people say they wouldn't choose the pleasure machine.

Well that was easy. In my (limited) experience most people making such claims do not really anticipate being pleasure-maximized, and thus can claim to want this without problems. It's only "real" ways of maximizing pleasure that they care about, so you need to find a "real" counterexample.

That said, I have less experience with such people than you, I guess, so I may be atypical in this regard.