why some people learn alot of programing languages ?

Answer 1

many times, it could be because of what their career is / what they aspire to be. with enough knowledge of a language, they can aspire for the job they wish with more of a chance.
also, sometimes they just choose to for the extra knowledge, or additive skills, using languages to shorthand the use of other ones, numerous reasons. its endless. ; w ;

Answer 2

One language is not enough. Each language has their purpose

Answer 3

Lots of time or curiosity. =)

Answer 4

Sometimes u learn how to use the previous one better by learning a new logic in new programming language