The system has evolved quite a lot over the years. It certainly isn't as bad as it used to be, where posting about your ratings was a surefire way to have them plummet:
![18-20102004.gif](http://benryves.com/gd_comic/18-20102004.gif)
Back under the very old systems a decade ago points were slow to accumulate and were based on people rather than posts. Reaching 500 or 1000 points required a lot of posts and popularity. it was very easy to lose reputation points, and a few people took efforts to keep their reputation at zero, the minimum value. The newer systems made acquiring reputation points very easy. Just like the entitlement culture, these days you get points just for showing up.
Even with the changes that have been made over the years, yes, there are a few people who misuse and abuse the voting system.
Fortunately there are many protections in place. An individual can only do a limited amount of damage in downvotes, and each downvote they issue has a cost to their own reputation that discourages the act. Upvotes are encouraged and rewarded.
Further, when people report abuses of the voting system (see the 'Report' button) we can look it over and take steps to repair the damage.
As currently implemented it is easy to get reputation points. A determined individual could easily boost their reputation by a hundred points in a single day with a bit of research and writing.