Intelligence is risky, the pitfalls are many. Maybe they got distracted and absorbed into themselves. The universe is also dangerous and dark, not everyone makes it. A star going out can be a depressing thing.
If a species is peaceful enough, smart enough, cooperative enough, and lucky enough to get to space without destroying themselves or being destroyed, maybe they did, billions of years before the earth existed. They lived, loved and died in a wink of the universe.
We'll find them someday, maybe. If we can exist that long. But we'll have to be here for almost an eternity, hoping that we see the day.
But when we do, it will be like meeting a lost lover. Another intelligence, a brother of mind in the stars. And they will feel the same.