I am not thinking about attacks for financial gains - if you already have 100 million Dollars there are probably better ways to get some more money than trying

I am not thinking about attacks for financial gains - if you already have 100 million Dollars there are probably better ways to get some more money than trying to double-spend Bitcoins. The really bad scenarios are probably adversary states or terroristic organization shutting down the circulation of money in case a state or a couple of states decide to use Bitcoin as the primary currency.