Guys like Mark Cuban entering esports is both a good thing and a bad thing.
Good thing is guys like him can give a good platform for esports to grow both financially and getting more fans. Imagine League of Legends being advertised at Madison Square Garden. Initially people will be like "what", but once they catch on, the viewer base and player base for LoL will increase in the US.
Bad thing is he is going to expect so much more from the players. In spite of him being interested in the game itself, he will be in it for the money. As of now, our players all over the world are pretty bad in front of the camera. cringeworthy bad. The level of trash talk and rivalry between the players is non-existent outside a very few incidents. While that is good in general, it is bad for a growing sport. People except drama so they can choose sides.