There is an infinite number of alarmist scenarios. We can not react to all of them. The argument that it would be too late if some thing x would really happen is not very useful for decision making.
For example a meteorite could hit earth and wipe out all life. Clearly we should pour all resources into building space ships.
For example a meteorite could hit earth and wipe out all life. Clearly we should pour all resources into building space ships.