I refuse to believe anybody is actually paying these amounts per click.
However, I’m pretty sure that if allocate a fixed budget, you could ‘buy’ certain keywords.
It’s in the interest of companies like Overture to create a continuous inflow of cash. They probably ‘sell’ terms for a fixed amount per month. Of course they have to make sure the customer receives a minimum agreed amount of clicks, so they set the ‘bid’ very high, just to avoid some idiot goes over it.
Receiving a fixed amount every month is better than the occasional casino that actually pays $50,- per click, but unfortunately stops advertising after one week, because they notice the RIO is not what it should be.