Ego gives us the illusion that we are separate from everyone else, which makes it very easy for us to hurt other people. Because we think we’re separate, we need to watch out for each other.
When we know we are all connected, we know that to hurt another is to hurt ourselves. That is why Ego is not necessary beyond a certain level of Human Evolution. This is exactly why Ego does not want us to evolve. The Ego is very much its own independent living entity and, like all living creatures, it will fight for its own life until the very end.