Google is a publicly held company, and they're leaving billions on the table.
Not necessarily. It would be a big risk pushing a Galaxy-level Google branded phone because it would destroy the relationships they have with partners like Samsung, LG, and now Chinese brands like Huawei. If suddenly those companies have to compete directly with Google maybe they look at forking the OS or replacing it with something that Google doesn't control. Android right now dominates mobile phone marketshare because of these partners, if Google stabs them in the back then they HAVE TO execute perfectly on their phones to not use marketshare.
And that itself is a very questionable prospect. Google really has never been a consumer products company. They really an advertising giant that ended up competing with Apple because other options (Web OS, Windows Mobile, etc.) couldn't get their act together. The few devices they have put out often have a beta quality to them- for example the first Chromecast was basically the beta for the current one.
Apple has always been a products company. First they sold computers, then they sold phones and other devices like routers. From the start they have been product focused, and they had a visionary in charge that could herd all the cats in the R&D side to put out a finished product that anyone can use. The leap for them into selling iPhones was much more natural, there wasn't nearly the risk that Google has trying to compete with its partners.
Microsoft shows what happens if Google messes up. The Nokia purchase was basically a huge waste, and Windows Mobile market position is in a worse place than it was a few years ago when Nokia was a separate company. There is no way for that platform to recover, as evidenced by Microsoft's increased development for iOS and Android. MS lost billions, which is the opposite of what you think Google's upside is.
Or look at what happened to Amazon. They are a much better product company than Google, have a MUCH better distribution chain than Google could build in years of trying, and their phone was a HUGE flop. Like legendary flop. I don't think Google's shareholders look at the Fire Phone as see a situation where Google is leaving "billions" on the table.
Google not making a Galaxy-level phone is a much smaller risk. Android will become the Windows of mobile unless they screw up that momentum. That means millions of eyeballs they control to feed their ad business, which is where Google's shareholders have traditionally seen value.
I get it, I promise I get it. People get sick of Apple's heavy handed practices so they pray to the heavens that someone will actually compete with them toe-to-toe on polish and style. Samsung looked like a viable competitor, but every year since the Galaxy S1 (which was basically an iPhone copy) they have eroded the consumer trust to the point that we know they cannot compete directly with Apple on polish and products. Apple is unique in its polish and product focus, more an exception than a rule.
We need to accept that no one will compete with Apple going forward. Just like what happened with laptops Apple is about to become the defacto high-end, and everything else will be choosing which compromises you can live with. That sucks for the OCD people that freak out because the gap between the screen and the phone is too big, but for the rest of us we are better served by a competitive Android marketplace. If Google back-stabs their partners that goes down the tubes.