How do we keep ourselves humble as researchers and intellectuals?
Staying down to Earth is different from being humble. Having concrete, non-lofty goals is different from being humble. 

The current academic environment does not encourage people to be humble, quite to the contrary. I am seeing many people whose career is built on preposterous grandeur.

What is different from being humble and a selling point is having a plan on how to make progress. If you have got lofty goals, fine, but then you better have a thought-through plan on how to make concrete progress in achieving your lofty goal. 

Knowing what you are talking about will set you apart from the crowd that just emits shedloads of buzzwords.