What do you understand by ‘not the common man’s cup of tea’?

Directions: Read the following passage and answer the question on the basis of the content of the passage.

The Universe is open and it is ceaselessly expanding. Space means the whole universe, including the earth, while outer space begins where the earth's atmosphere ends and extends in all directions. The study of space and of outer space is, of course, not the common man's cup of tea, but the interests of mankind are deeply involved when space is put to certain uses, not all of which are peaceful. The use of space for civilian flights within a country and for the worldwide air services has brought mankind and continents closer than they ever were. In a matter of hours, a person can fly from one continent to another; the communications gap has been reduced by what seem to be fantastic means through space.