There are two possible interpretations here, the cynical and the optimistic.

**Note that I am not naming any specific parties and for the purpose of this answer am not taking any side.**

**The cynical**: After looking at the demographics as they apply to you particularly, they've calculated a high chance that if you were to vote you would vote for them, therefore they're trying to encourage you -- and as many others in a similar demographic as they can -- to vote. 

After all, who wins the election ultimately depends on how many people actually went out and voted for a particular candidate, not just how many people sided with them or agrees with their position.

**The idealistic**: The whole *point* of living in a representative democracy (or a republic if you're going to insist on semantics) is that the government reflects and represents the will of the people as best it can. Which means that the more people vote, the better the system works. And if you honestly believe that you're in the right, and that the majority of people will side with you, encouraging absolutely everyone to vote is no more than the right thing to do.

I personally prefer live in a world where the idealistic answer is correct. So go out and vote.

**EDIT** [Jontia](https://politics.stackexchange.com/users/18367/jontia) put it better than I did in [their answer][1].


  [1]: https://politics.stackexchange.com/a/59149/4778