How is it possible to calculate the block formation time of 10 minutes?

Question

bitcoin

Hello. On the one hand, they say that it will take millions of years to decrypt the hash, given today's power, and on the other hand, they say that the average block formation time is 10 minutes.

spoiler

I see blocks that took 2 minutes to form, but it's still not that much of a difference. According to my logic, we should see blocks that have been formed for 5 years, and not these 2-10 minutes...
If the hash is so random, how did they get the formation time?
Here, look, the task: The car goes from point A to point B. The speed of the car: 100 km / h. Find the time it takes the car to get to point B, given that point B is in God knows where.
Correct answer: about 10 minutes. And I'm wondering why is that?
Why does it take them about 10 minutes to get a particular hash, but millions of years to decrypt a hash?

Answer 1

The hash itself is calculated quickly. The problem is that you need to pick it up according to the conditions. For bitcoin, this condition is set by tn complexity. This condition changes about once every two weeks so that the speed of calculating the hash and creating a new block is approximately constant (10 minutes). Thus, the viability of the network is maintained, there will be no distortions if there is a lot of power (roughly speaking, protection against capture, and not only), but there will be no super long waits for a new hash if all the miners leave, the complexity of the calculation will decrease and a few will be able to look for new hashes again. which means it will become profitable and the miners will return.
At the same time, the reward for calculating the hash for the block is periodically reduced, which again is not a problem, since the system is being rebuilt to work through commissions.

Answer 2

To control the hash search time, there is the Difficulty parameter, which constantly changes depending on the network load, the number of blocks mined ... If the block search time increases, then the complexity decreases and the block search time is adjusted