Is there really more demons than those of the fallen angels? My answer is yes. We know for certain that Satan started a rebellion against God and man. Satan was able to take one third of the angels of heaven and make them rebel. A large majority of those fallen angels are now imprisonment.
There was already demons in the earth before Satan started that rebellion. In the beginning was Adam and Eve. 'The devil', which is a snake, a dragon, called Leviathan, tempted Eve and who then tempted Adam. It is 'The devil's' curse to eat the dust of the earth all the day's of he's life. He had already been in the earth fighting a war against God. They are snakes and scorpions. I cannot tell you at this time where scorpions came from, because I do not know.
Satan and the devil work together to fight against God, trying to bring God's judgement on the men. A silly and stupid war, to fight against God. It's not worth being an enemy of God. God is good, and forgiving, full of mercy and kindness.