Exactly, Sith go on blind rampages with no real goals. They destroy because they can. To what end? They don't care. Power itself is rarely the goal of a group or an individual, power is a tool to achieve other things e.g. government, freedom, wealth, pleasure, peace etc. The Jedi don't want power, they only want peace. Most Sith just want power for powers sake. This is where they fail because if they continue to pursue power with no real goals or aims, the power will consume them, their quest will eventual end and they will be destroyed. The Emperor was paranoid, and his quest for power drove him to insanity. The quote shows he had become trapped in a perpetual cycle of a never ending quest for power which could only end one way: with his inevitable destruction.
And yes, Sith meditate. But they rely on emotions to achieve immediate power. Sith sorcery and meditation are just steps towards achieving true power, in ways other than grasping blindly for it.
And about Traya, other goals? She was the only Sith whoever had a goal that didn't involve claiming power for powers sake.
there are no such things like "real goals", every goal is worth the same. To experience everything you want, first you require unqustioned power. In the SW vast galaxy those who want everything are obliged to go after it. Peace is a lie, a key to progress was always in passion, chaos in form of war or any other form that pumped need of advancement, Sith enjoy their infinite combat voyages, it is their purpose, to test themselves.No one can become consumed by power, it is just a quote people like to use when their relatives achiev something, do dirty things and alienate themselve. Sith are ready do destroy and be destroyed, they dont ask for mercy nor give it. They are much more fulfilled in their lives than jedi who whole their lives supress emotions and are at conflict with themselves just because code says so.
hes far from paranoid, he was even calm when JK caused some troubles. he doesnt care for little flies.
that quote says that he wants to live however he want to, unrestricted by laws of a mere mortals. He is definately not insane, hes simply intelligent beyond measure of those who sorrounds him. after all, he lived for 36k years after TOR, so he will Survive this battle and any that will become - and what I can speculate about his death is that he chose it for himself after he got bored
and Traya wasnt exactly the most calm person from what I remember