Other calculations put the number of solar systems within 100 light years of earth at about 170,000. Still a far cry from millions. 100 light years is a good measure because the oldest radio signal from earth has traveled about 110 light years. How Far Have Our Radio Signals Traveled From Earth? The other problem is also addressed at that last link...
While it’s interesting to imagine how far our radio signals have traveled into space, it’s extremely unlikely that an alien civilization will be able to catch the latest episode of ‘I Love Lucy’. This is thanks to the inverse square law. In Layman’s term, it’s a form of signal degradation.As radio signals leave earth, they propagate out in a wave form. Just like dropping a stone in a lake, the waves diffuse or “spread out” over distance thanks to the exponentially larger area they must encompass. The area can be calculated by multiplying length times width which is why we measure it in square units – square centimeters, square miles, etc. This means that the further away from the source, the more square units of area a signal has to ‘illuminate’.
In addition you have to figure the odds of life being present in any given solar system and the number drops a lot from that 170k. Then figure in the odds of that life being intelligent and technologically capable of "listening" for radio transmissions and it is narrowed down to some small fraction of a percentage point.
"There are a total of 115 stars in 81 star systems within 20 light years from the Earth."
But no calculation about 100 light years containing 170K stars.