It does not hurt to emphasis this point: Google makes almost all its mega wealth from advertising! Since its services are free, such as its search engine, it makes its money by selling advertisers your personal information that you directly and inadvertently give Google.
It hardly makes money off stuff like its mobile phone service, its own computers, televisions, Internet browsers, etc. Google expands into other business platforms because it feels that it needs to in order to control power and stay relevant. It had to get into the phone business in order to make sure its services worked on mobile devices people were using because more and more people are now using mobile phones to do search. What matters to them is that advertisers continue to come to them.
Which companies are paying Google click here
Recommended furthur reading, click here