There is an adage in South Asia which literally translates to: A camel has finally seen the mountain. Which basically goes back to a story where a camel used to think that it was the tallest until it sees a mountain and it realizes that it isn't and there are things taller and bigger than it.
Here is an example usage: BlackBerry used to think they were the biggest in cell phone market until they saw Apple; the camel has seen the mountain.
Is there an expression in English for this?