Democide is horrible any way you look at it. It is a horrific action, and cannot be tolerated anywhere in the world. But the bigger threat is the idea that other countries will have to take sides. Some countries will support the government democide, while others will fight against it. This causes more tensions and can lead to war. Large scale wars, which can be causes by democide, are the biggest threat to humanity.
I feel that obesity and work accidents contribute more to death than democide. Its not often that you hear of governments killing mass amounts of people these days. However you hear about peoples lack of healthy lifestyles becoming a big reason for the death of a person. Also lack of safety in jobs do contribute a bit more these days.