Either that or they just don't think about it too much. I've seen plenty of people convince themselves of some pretty stupid shit or ignore/contradict past statements in a way that seems willful but isn't - you can usually get them to untangle and rectify their thought process if you point it out to them, but politics doesn't really provide that avenue. Politicians live in their own bubble and people paying attention have maybe 30 minutes ever at the absolute most to try and point out how inane and self-contradictory some of their positions are.