Google did not do this out of the goodness of their heart. They did it to lock you in with Firebase, Maps, etc. And believe me, the moment they start charging you for it, you quickly realize why Google is not a company to give an ounce of trust to.
Eh, I think you’re underselling the value of “free” stuff. Even if it has an ulterior motive, giving free access to computing resources allows someone to learn concepts and even ship things that would otherwise be impossible.
None of these companies are altruistic and everyone knows it, but by not charging upfront it gives possibilities for millions of developers who don’t have US$ 50/month to spend on something (students, emerging economies, career changers, etc).
I wouldn't as knowledgeable and successful in tech without free computing resources from various companies. My parents didn't have any money and I certainly didn't either.
There's a lot of transferable skills gained in these products. You're not just operating a Maytag.