Why do Political Parties win elections?

A political party is a political organization that seeks to attain and maintain political power within government, usually by participating in electoral campaigns. - Wikipedia

This is a sad state, Don't you think? This definition of a political party only talks about attaining Power.

I saw a recent poll on IBN site where a whooping 71 percent said YES to the question, "Are Independents doomed to fail in the General Elections?"

Why are a majority of independents losing, and political parties winning? Despite all of us knowing that the parties will not even do anything to improve the living conditions of the people?