There's an argument against democracy that claims it can lead to mob rule. One common quote is that "it's two wolves and one sheep deciding what to have for dinner". See also tyranny of the majority.
There's a wide range of how much of the population gets to make the big decisions.
If only 1% of the population gets to make the decisions, then 99% may suffer.
If 51% of the population gets to make the decisions, then 49% may suffer. While 49% may suffer, this is not a valid argument to support allowing 1% to make the decisions, which would be even worse.
If you require that 100% agree before a decision is made, then nobody will suffer, but decision making becomes harder and harder.
There is an anarchist concept known as decentralized democracy. That means the more someone is affected by a decision, the more say he has in that decision. If a decision barely affects 99% of the people, then none of them get to vote. The decision to kill someone affects the victim more than anyone else, so the victim should have more say in the decision than everyone else. The decision over what you eat for lunch barely affects anybody else, so obviously you don't have the entire society voting on what you have for lunch. In cases like these, it becomes a democracy of one - thus anarchy.
Supporters of decentralized democracy would use their own power to protect the right of others to make the decisions that most affect them. For example, this includes protecting other peoples' lives, whether it's from government or non-government forces.