Every business has dependencies and suppliers. This includes the magical Google. Did you ever notice how many copyright notices appear at the bottom of every Google Maps page? Did you ever wonder why those are there? It's because Google licenses data and technology from third parties to make their Maps product happen. How does the data get there? That's right, through an API.
An API is just another kind of supplier. Every business can be disrupted by its suppliers, and that's true for APIs as well.
As a thought experiment, to test how sensible this rant is, replace the word "API" with the following other kinds of suppliers: hosting provider, internet service provider, payment processor, employees. All have the potential to disrupt your business. What matters is what your contingency plan is.