Take for example bitcoin. People are paying thousands or even million times more for bitcoin than for some altcoins
Correct.
even though these coins have the same or better utility than bitcoin.
Nope.
There is no altcoin in existence today that has "the same or better utility than Bitcoin". You are mistaken.
Meaning, the same as bitcoin these coins can be transferred easily, fastly, cheaply, safely and transparently to someone.
Some can be transferred faster, some can be transferred cheaper, some can (perhaps?) be transferred more safely, some can be transferred with more transparency, some can be transferred with more anonymity. However, NONE are able to match ALL of the features of Bitcoin. Whenever they are better than Bitcoin at ant one thing they are worse than Bitcoin at others. Most are worse than bitcoin at the things that really matter (such as security), and better than bitcoin at things that don't matter as much (such as blocksize).
Such coins can be bought for as low as $0.001. Why people in the crypto world pay millions time more for the same thing?
Because it is NOT the same thing.
Why they behave so irrationally?
The behave VERY rationally. Your failure to see the difference doesn't mean that the difference isn't there.