I think you might be mistaking a lack of blockbuster success (so far) for a lack of ambition. Sometimes success is what makes the company or person look ambitious after the fact.

If Google had not succeeded, it would be easy to say that they lacked ambition - they just tried a me-too search engine when Yahoo! and AltaVista were the titans. But Google caught fire and now, we all think they were audacious and ambitious to try what they did.

Ambition alone does not guarantee success: sort of a necessary-but-not-sufficient ingredient.