Skepticism, Science & Pseudoscience

Technological civilizations have a v high probability of destroying themselves and, in time spans that are essentially infinitesimal compared to geological or cosmological times. Our example of one i.e. earthlings, have been a "technological" civilization only for a couple hundred years or so but even in that short time span, we have come close on more than one occasion to nuclear annihilation and are in serious danger of future extinction by additional means such as mass starvation or disease and/or environmental collapse.

So, over the eons of time there may well have been many technological civilizations briefly come and go within our galaxy but almost never more than one at the same time. That's the situation we are probably in now.