I don't know how I would get a $100k bill from a spike. That ignorance is enough for me to avoid using the service - unless I know how the billing works, what my maximum monthly bill is going to be (with a hard limit that cannot be crossed), and exactly where all the gotchas are then I won't use the platform.

Auto-scaling magic is lovely in theory, but in practise it is hard.

Annecdata - a video streaming startup here in Newcastle that enabled DJs to stream live sets was used to illegally stream some football games. The subsequent bandwidth bill killed the startup. Yes, they got some things wrong with their tech, and security, but that's the danger that put's people off using "clever" services.