But the 500 planets studied are the rule. Too cold, too hot, too irradiated, too something. Study 500 million planets and you’ll find the same thing: The conditions for intelligent life are incredibly, infinitesimally rare.
As long as we're using our current technology which can only infer the presence of super-massive giants that are tugging on their parent planets, then yes, what you say is correct.
Give our technology a couple of generations to improve, and we'll be directly sensing small rocky planets like our own.
The chances of finding earthlike planets will then increase exponentially, as will the chances of discovering evidence for life on them.