You are wrong.
Example that should make it clear....
Example that should make it clear....
Wait... no... that example is only valid for the "attacker takes over existing mining pools" case, where formerly honest miners are co-opted to be evil (or gang up in a cartel to be evil).
If somebody collects as much hashing power as the rest of the network combined and then suddenly attacks, then yes, indeed, difficulty stays the same, the attacker gets all the mining rewards, and there are twice as many stale blocks as before. Attacker gets 6 block rewards per hour.
If they were to mine honestly, blocks would be created twice as fast until difficulty adjusted, so they'd get 6 block rewards per hour for a week (same as if they decide to attack). Then difficulty would double, and they'd get only 3 per hour.