At this exact moment humans do not need to move to space, however in the future it is plausible. It doesn't hurt to get another means of living ready just in case. With how warm the earth has been getting each year it is possible it will eventually fail us and we will need a new home.
To avoid a mass extinction, which could occur at any given moment, a species must spread as far out as possible to insure their survival. This would essentially reduce the chances of a specie specific extinction such as a plague eliminating the human race or a major event such as a rogue asteroid destroying earth.
I believe that it's best that the human race works hard to find ways of space exploration. I think finding another planet will have great ways of our survival, for just in case something happens to our original planet. I think we could survive better as a people since we wouldn't need to worry about what happens to Earth.