What would anyone who doesn't care enough do? If they don't vote, they increase the power of other voters. If they vote randomly, their votes would cancel each other out on average, making it as if they hadn't voted. If they vote based on what somebody or an organisation says, that person/group is empowered based on the number of followers.

This is the main issue with FPTP voting. If you wish to disempower fringes, require majority approval.