I am concerned about it either. For example one of my question got 4 downvotes and 2 upvotes, what is very unusual. In addition, I see that all active members gave out almost 0 downvotes, maybe with one or two exceptions. That means some people have "trashes" account for downvoting others and upvoting themselves. 4000 points is huge pool of points, and that would be very dissapointing if someone will ruin one year effort in one week by unfair downvoting. In my opinion, points for voting should be decreased, and points for downvoting should not have any impact on reputation. Punishing someone for trying does not encourage to activity.
This solution won't stop cheating, but will give a chance for fair players to get their 4000 points. At now, I don't even try to ask more questions, because I will loose more points than I gonna receive.