Future of the Salary Cap?

[BFritz21]

The salary cap went up by 16.5 million from '05 to '06, then was relatively stable for a few years, and then has gone up by 10 million each of the last two years.

My question is, when does it stop? Will it continue to just go up until the top tier players are making even more insane amounts of money than they are now?

Seems weird to me that I don't think normal people's salaries are increasing at these exponential rates, so how is it rational that the athletes' salaries are?

I realize that the owners are billionaires and have change to spare, but will it ever stop or will top tier football players just become some of the richest in the country?