I think what happens is, people often become believers through family, culture and quite often they hear these emotion stories about how Christ died for them etc etc. I believe countries like America do a good job [as in successful] of selling the story of Christ.
So when it comes to the global flood it's quite easy for people to use things like miracles and statements like "things were different back then" to get around the problems these ancient tales all possess.
Kurt Wise, a famous Christian scientist famously said that even if all the evidence in the Universe was against creationism, he'd still believe what the Bible says. After all, if they doubt the flood or any other story, then the Bible essentially becomes useless.
At any rate, getting to the reason I posted in the first place. If I remember right, most creationists claim that the K-Pg boundary was caused by a meteor but DURING the global flood and not 65 million years ago. I can only fathom the waves Noah would be encountering on his year long trip.