Luke that "As in the days of Noah, so shall the days of the coming of the Son of Man be. People were eating, drinking, marrying and being given in marriage up to the day Noah entered the ark. Then the flood came and destroyed them all.
Of all the people, only Noah's family was saved Noah warned the people that God's judgment was coming. It took hundreds of years to build the Ark, and everybody knew why Noah was doing it. But nobody believed him until it was too late.