Why don't other civilizations take the initiative to contact the earth people?

First of all, if there is an alien civilization, there are three possibilities for this civilization:

1. The level of civilization is lower than that of the earth people.

Forget it, they can't get in touch with the earth people.

2. The level of civilization is similar to that of earthlings.

Don't even think about it They have no ability to contact the earth people.

3. The level of civilization is much higher than that of people on earth.

A high degree of civilization means that this civilization can at least observe that there are earthlings on the earth and confirm that earthlings have developed civilization (not all livable planets can produce life, nor all living planets can produce civilization, and it is very likely that the creatures on some planets will remain in the stage of monster struggle until the collapse of the star system).

In this way, civilization must have mastered the observation methods that the earth people have not mastered at present, and can accurately see the state of a planet in other star systems. This way is obviously unimaginable for modern people, just as people in age of steam can't understand electricity. Further suppose that this civilization wants to communicate with a civilization whose civilization level is far lower than its own (in fact, this is also a small probability event, and it doesn't make much sense for this advanced civilization to communicate with people on earth when it can't reach the earth), and they will choose to send signals to people on earth by their own information transmission methods (because they simply don't know how people on earth transmit information). However, if you send electromagnetic waves to people in age of steam, can he receive them? After a long time, he has observed this electromagnetic wave, and he won't think it's your signal. Similarly, people on earth probably can't receive or understand this signal correctly. So for the earth people, it is equivalent to no contact at all.

See, I assumed so many small probability events (alien civilization, high degree of civilization, willing to communicate with the earth), and finally I couldn't get in touch. Civilization is doomed to be lonely in the universe, because the universe is too big.