I think the song "Vicarious" is about a lot of things. But i will pinpoint what I think Tool meant it to be about.

In the song not i think the band is reflecting on how as humans, we have these things inside of us.

Cause I need to watch things die... from a distance.
Vicariously, I live while the whole world dies.
You all need it too - don't lie.

I think its easy to see what Maynard is singing about here. He is talking about our hunger for emotion and change and he is admitting that we all have it.

We all feed on tragedy.
It's like bood to a vampire.
Vicariously, I live while the whole world dies.
Much better you than I.

"Much better you than I". Its very evident here what he is saying, that we love to watch Tragedy and its even better when its somebody other than yourself.

As a whole, i think the song is adressing the issue that we have these thoughts, feelings, desires (maybe on a sub-conscious level) that we just wont admit to. Maybe we are ashamed of them?