My latest post in the @dbuzz 30 Day Challenge was for Day #20 and the topic was, "Do you think there is life on other planets?". I buzzed about the Prime Directive and used the limited number of characters in the micro-blog to paraphrase a few lines from the Star Trek: TOS episode "Bread and Circuses".
The topic happened to coincide well with the latest Isaac Arthur YouTube video about the Drake equation.
As Wikipedia states:
The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy.
Fundamentally Drake's equation is a just that, an equation. It can give an estimation of how many alien civilizations likely exist but it can't determine where the civilizations might be located or how many exist currently.
As the video points out many of the factors have unknown values. Since the equation was first proposed astronomy has progressed and more is known but the factors still have large margins of uncertainty. The absolute minimum result from the equation is 1.0 (Earth). Without more evidence of techno-signatures or better understanding of exobiology any number predicted higher than one such as ten thousand or ten million is pure guesstimation.