Think about the words "Draining the swamp". What do you visualize?
Personally, I imagine a swampy, murky body of water, where the water is dark and you cannot see the bottom. Would be pretty scary to go across, right? It's a basic human instinct - we fear the unknown.
Now imagine all of that murky water starts draining away. You slowly begin to see what's in the swamp. And, unfortunately, your fears weren't unfounded. The swamp is full of gremlins, swamp creatures start emerging from their safe hiding spots that were once underwater.
Now, what happens to any living creature on this planet when you suddenly take away it's home and the feeling of safety? They start to panic, the fight or flight response kicks in.
And your fear of the unknown has gone away. You now have many different options - you can plan the most viable path to cross the swamp, you can fight the gremlins, most of them might just run away.
Trump HAS drained the swamp. We know every traitor by name, we know their crimes, we know the extent of their degeneracy, and we are no longer fighting against an invisible enemy. They fear our knowledge, in fact they cannot function with us knowing. All of their tricks that have worked for decades have been exposed and have become useless. The whole world knows, even my 79 year old grandmother and grandpa know and share these things with their close friends. The swamp has been drained, all of the creatures living there are in full view for the world to see.
Exposure. Declas. Fraud. Now "we", as a whole, see what only few have believed.
Seeing is believing