1. From Earth, we can see Billions of stars, trillions including galaxies where we can't make out stars individually.

2. The Universe is approx 13 billion years old, which is a lot of time for life to emerge and multiple generations for large stars. Life has already emerged in one place at least in that time.

3. Under known physics, it should only take 2 million years at most for a civilization which has advanced to space travel to colonize an entire galaxy, if even a tiny tiny fraction of them want to.

4. If there are any civilization out there, we should see clear evidence of it. The fact that we can see stars at all should be surprising (this is known as the Dyson Dilemma)

https://www.youtube.com/watch?v=QfuK8la0y6s

5, Among those billions/trillions of stars, we have not seen any evidence of extra terrestrial civilizations.

Why don't we see any evidence of extra terrestrial civilizations?

You can choose multiple answers, but keep in mind if they are compatible with each other (don't choose multiple incompatible answers).

Answers are pulled from wikipedia

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Extraterrestrial life is rare or non-existent (15.79%) 12 / 76 Intelligent civilizations are too far apart in space or time (14.47%) 11 / 76 We are not listening properly (9.21%) 7 / 76 Human beings have not existed long enough (6.58%) 5 / 76 They tend to isolate themselves (5.26%) 4 / 76 They are too alien (5.26%) 4 / 76 Earth is deliberately not contacted (5.26%) 4 / 76 They are here unacknowledged (5.26%) 4 / 76 It is the nature of intelligent life to destroy itself (3.95%) 3 / 76 Periodic extinction by natural events (3.95%) 3 / 76 Earth is purposefully isolated (planetarium hypothesis) (3.95%) 3 / 76 It is dangerous to communicate (3.95%) 3 / 76 Intelligent alien species lack advanced technology (2.63%) 2 / 76 Lack of resources to spread physically throughout the galaxy (2.63%) 2 / 76 Civilizations broadcast detectable radio signals only for a brief period of time (2.63%) 2 / 76 No other intelligent species have arisen (1.32%) 1 / 76 Water world hypothesis (1.32%) 1 / 76 It is the nature of intelligent life to destroy others (1.32%) 1 / 76 It is cheaper to transfer information for exploration (1.32%) 1 / 76 Colonization is not the norm (1.32%) 1 / 76 Outcomes between all and nothing (1.32%) 1 / 76 Other explanation (explain in comment) (1.32%) 1 / 76