Why do cis people always say that?

In order to describe trans people's gender dysphoria to cis people, lot of people seem to ask "If you wake up having the body of your opposite gender one day, how do you feel?". As a transmasc person I indeed feel like I suddenly woke up in a girl's body, so this question makes perfect sense to me. However, when I ask the same question to cis people, most of them answer "It would be fine, I would live as the opposite gender with no problem." and it confuses me so much... Why do cis people answer like that if they identify as their AGAB? I don't understand.
Edit: Please stop attacking cis folks in the comments, I didn't intend to start an argument. Please be nice to people.