What is the ruling on investing and trading in internet cafes, given the ignorance of what the user will access, and the possibility of them being used for chat programs between sexes where forbidden pictures and films are exchanged?

If devices are used for reprehensible matters that harm one's creed, or for viewing obscene images and films, or vile news, or suspicious chats, or forbidden games, and these reprehensible acts cannot be prevented, then trading in them is unlawful, because it constitutes aiding in sin and forbidden acts. Allah Almighty says: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression. And fear Allah; indeed, Allah is severe in penalty).