Las Vegas is a huge tourist attraction especially for people who live near the city much like Disney and the Cruise Lines are to Floridians, if you make it easier and fun for people to travel then you have a chance to be successful
They are probably are already looking at the number of people who travel from LA to Las Vegas and have calculated what percentage of them they need to convince in order to be successful, they are not trying to invent a new market but participate in an existing market
A lot of Raiders fans still live in LA, so I can see them making the trek to LV for the Raiders home games.