The days of Noah were some really bad days. The Earth was populated with 10 generations of men, from Adam to Noah (Noah being the 10th generation from Adam). The average natural lifespan of these generations was 900 years - many generations overlapped previous generations. Each man had many sons and daughters throughout their lifetimes, so there were many, many people populating the Earth.
How are we, as Christians, supposed to approach people that want nothing but what is evil? The world seems to become more and more evil by the hour.
It is of utmost importance that as you travel down the path of studying end times prophecy (eschatology) that you never lose your focus on your job to make disciples. Our job as Christians is first and foremost, the Great Commission - Matthew 28:19-20.