I have a question for those people who believe in overpopulation?

I believe serial killers & terror-bombers should be killed,QUICKLY!; both groups have no value for life whatsoever. However,we do need depopulation for the reason that there are only so mutch resources on this earth to support life comfortably. Do you wish to live a miserable existence on earth because of to many people for earth to support. The truth is; the more people=the less for everyone. How many people do you believe the earth can support----for how long?