There is no simple answer to this question. Different ad networks, affiliate programs, etc. each charge different amounts to advertisers per click. There are also other factors that can impact the CPC cost, such as competition between advertisers that are bidding against each other. Obviously, if a CPC campaign is no longer profitable for an advertiser due to high CPCs, then they will stop the campaign.
In the case of many PPC platforms like Google AdWords, they have what is known as a quality score. The quality score is based on various metrics and adapts and changes dynamically. The higher an advertiser’s quality score, the less CPC they will pay, whereas a lower score will increase the CPC. Many networks do this to improve the user experience and to level the playing field for advertisers.