Charles Hoskinson was one of the co-founders of Ethereum, but he left the project in 2014. There have been many rumors as to why he left, but the most common one is that he was kicked out by Vitalik Buterin.
Some people believe that Hoskinson was kicked out because he disagreed with Buterin on how the Ethereum project should be governed. Others believe that Hoskinson was simply too difficult to work with and that Buterin wanted to get rid of him so that he could have more control over the project.
Whatever the reason, it is clear that Hoskinson is no longer involved with Ethereum. He has since gone on to launch his own blockchain project, Cardano, which is currently ranked as the 5th largest cryptocurrency by market capitalization.