Charlie Lee as a founder of Litecoin and Vitalik Buterin as the founder of Ethereum projects both sold their holdings at the peak in 2017 bull run. Their unethical behavior was priced in the market right after their dump but the market participants didn't know this fact until they publish this information. As the founder of projects, they have the rights to choose what they going to do with their altcoin holdings.
That's true that they have the right to dump such massive amount to the market but I hope they won't just straight out dump their coins at the same time which could result in massive dumping considering that they are not holding some measly amount of coins. Though, in the eyes of people to sold a really big portion of Ethereum may seems unethical. But, people have different opinion.