If you see a comment or article you approve of, you should upvote it, regardless of how popular (or not) it is among other people. If there are 529 people who approve of a certain comment, then it comes by those 529 upvotes honestly.
Everyone thinks they're just giving them a little bit. But all those little bits add up to a lot. Without any visibility into how much other people have already given them, there is no way for people decide if they really need the money or not.
If you saw a beggar on the street, and knew that they'd already been given $1000 so far that day, would you still give them a dollar?