If you go to the Targum Onkelos, the Aramaic translation/paraphrase, you get v’it’p’lag, “And he separated himself”. Now we have two new questions: what is meant by “he separated himself”, and how can Onkelos justify this as a translation of vayikkach?
To take the second question first, it seems that Onkelos takes the verb as reflexive – who/what did he take? Himself! He moved from one side of the people to the other. He claimed to be a democrat, seeking the welfare of the whole community. In fact, he became a despot. It’s as if he said, “I’m the one in charge: I decide what’s happening!”
When one of my children was very small she refused to do what her parents wanted, and she said, “I’m the boss of me!” It was a sign of independence, but to be the boss of oneself is far less than what Korach did. With him it wasn’t simply “I’m the boss of me!” but “I’m the boss of everything!”
The context is Biblical, but the problem is as modern as today. It’s what we see these days – someone claims to be a democrat when in fact the person is a demagogue and despot.