Unlike display ads, PPC ads are placed directly next to a competitor. Display ads track website "conversions" (what action did a potential customer take on your website) whereby PPC strategies simply measure the CTR, (the click.)
Showing your text ads on the Google Search Engine Results Page when a user searches keywords related to your business, across all devices. In theory, PPC makes sense: the people clicking are actually interested in your company. As a Forbes article states, "With Google Ad Words you're paying for clicks. That wasn't a problem a long time ago when rates were more reasonable, you know, pennies, instead of dollars. The problem nowadays is a business is dropping $5 or more per click to get people to visit their site. Sure, that may increase visitors because you're appearing at the top of the Goodle search page, but it's not guaranteeing customers. Some clicks can be as high as around $60 range per clicks."
If your company operates in an obscure industry, the cost to get to the top of PPC may not be very high. But, for most companies, there are many other competitors also bidding for space for the same keywords. Instead of paying pennies for each click, you might find yourself spending tens if not hundreds of dollars just to get a click.