Many times it's just the fear of losing. Aka if you are hp you are paying for the printer keywords out of fear that Epson might take them instead
But because it is a monopoly currently businesses pay way more than the value of the actual conversions Google ads achieve.
Nobody should be willing to pay above, yet they do because the competition is willing to speculate on the value of these and take extreme positions.
You can test it yourself. Try to promote your website with Google ads and you will see the insane prices they ask for. Btw you don't know if someone else is paying that number, google tells you that that is the price.