Coinmarketcap is a free service that is making its cash most especially from those ads you are looking at. It is left to you to know what to click and what not to click.

Moreover, most of these sites make use of a service like googleads and co which usually push any ad to the page and there is nothing you or coinmarketcap can do about it as long as they need funds to keep being operational. If you don't like seeing them, just get an adblock.