There's no shortage of discontinued products that were cancelled even though a lot of effort and money was poured into them. Amount previously invested is a sunk cost and shouldn't even matter when deciding if continue a service/product or not. Just because you have already dig a hole doesn't mean you should keep digging even though you can't profit from it.
Shouldn't but does. It has it's own fallacy section:
https://en.wikipedia.org/wiki/Sunk_costs#Loss_aversion_and_t...
Also, not falling for the fallacy means admitting defeat. And the higher up one is in an organization, the worse admitting defeat is for your career. Having a product dead-ended by keeping on working on it forever is much better for manager/government official careers. So sadly, the fact that other people (above you) fall for the fallacy makes falling for it yourself rational in a lot of cases. Instead just systematically lower the priority, but never to zero.
In anything but a startup, I would treat any sunk cost above a minimal level as a firm commitment to continue at any cost. I would never have done so 5 years ago, but ...
Hahahahahaha. Aight. Whatever you need to tell yourself. This is even sillier than Parse; FB doesn't have anywhere near the track record of killing projects that Google does.
Whenever there is a Firebase announcement there are many replies along the lines of "this won't work for me because it's owned by Google, may be discontinued, doesn't have on-premise solution, etc". If these are your thoughts then you are missing the point of Firebase. It enables small web development shops like mine to focus on building beautiful web applications without having to give up manpower toward backend engineering. The cost of using Firebase is peanuts compared to the savings in employee hours.
Perhaps some day we will have to migrate elsewhere, but I find that possibility extremely unlikely because the clear amount of effort it took to create the Google-y version means this is a long-term play.