Answer:
Probably because they don't want people who did vote to get mad at them for their decision. It could also be because they don't think that voting does anything or helps them for the future, or because they just don't like politics. It could also be because they don't want to put someone in office and then realize that they aren't a good person, and then they are part of the party responsible for endangering the public by putting this person in a place of political power.
This is why if you are of age, you should always vote, even if it doesn't concern you.