And chess.com has more money to spend, so they can have things like paid grandmasters streaming, video courses, offical tournaments with large prizes. It's not all ad based, they also have a subscription model that opens more features.

It's good that both exist. I spend 99% of my online chess playing time on Lichess but there are also lots of people for who it is the other way around.

chess.com was founded in 2007. lichess started in 2010. So chess.com was already an established player.

The point is that creating a new chess site today would require to be better than lichess. If we look where Magnus Carlsen investment goes, they are all paid services (Play Magnus/chess24/chessable). He doesn't event try to compete with chess.com/lichess.