Google doesn't get to be Google without spending a crap ton of money, so it should come as no surprise that Google spend $7.2 billion getting its apps and search bar onto your smartphone.
Google has been paying Android partners to place search bars on their homescreens, and include pre-loaded apps like YouTube and Chrome. The search giant even pays its biggest competitor, Apple, so that Google can be the default option for built-in search box placement in Safari. Google says that the $7.2 billion is their "traffic acquisition costs", with the amount increasing every year.
Google spends over $19 billion on traffic acquisition per year overall, with nearly half of it getting their apps and services on as many smartphones as it can. But the company is running into walls with EU and US regulators concerned, which has investors worried as well. If regulators start pushing, they could allow OEMs to renegotiate their agreements with Google, and even leave their contracts.
Things can change very quickly for Google, and I'm sure we're going to be seeing these changes in the next 18 months.