my view is that if you're serious about "building product", then you wouldnt work at google, or Facebook, or for anyone else. You would build and run something yourself.
If you like the "building" part but are indifferent about "product" then somewhere like Google seems great.
> if you're serious about "building product" [...] You
> would build and run something yourself.
And sometimes those devs go into business for themselves and realize that they don't get to spend all their time building product -- now they've got to build the marketing page and write a bunch of copy and take a ton of screenshots (of features they know they're going to change), and figure out how sales funnels work, and all the other things that go into running a business.
Building and running your own company is the fastest way to get out of pure product development I've ever seen.
I think that if you are passionate about creating a product for people to use, then you will see through on all the other aspects of making that product survive and be used.
Otherwise, what you're interested in is "development", and big places like Google will give you plenty of experience in doing that.
This is not a value judgement. Personally, I have no problem working at a company where I'm paid to engineer products from the ground up. Maintaining things is boring. But that's just me.
If you want to build an original product, then yes, it can happen not to align with a megacorp's priorities, even if reasonably successful. Found a startup, try to sell it to a megacorp (if it's Google, it will likely discontinue the acquired product anyway), or keep it to yourself if you can afford it.