On-line Game or Single player Game?

On-line Game or Single player Game?
For now on line game are more popular than single player game but the most video game company still like to produce single player game.
If a video game company produce a very popular on line game, they can get more benefit than they produce a popular single player game. Because the company do not only get gain from sell the software, the company also can get gain Internet, because if the players want to play on line game they need buy the software and pay for fee when they play the game on line.
But the video game company still like produce the single player games, because the player play the game need still pay for the on line fee. So the most of player just like to play one on line game for a long time. They do not like to play several on line game, it cost too much money and time. So if the company produce a on line game cannot be popular the company will lose a lot money, because the on line game also need the company to pay for servers. Produce a on line game will spend more money and more time than a single player game, and the on line game need to keep updating. The opportunity cost of a on line game is more than 2 single player game. For example the Blizzard a very famous video game company in the America, after the World of Warcraft which on line game the Blizzard produced began to servers. They have more than 1 year no have new single player game to promulgate and the single game they began to do before the World of Warcraft is still delay.
What is the better choice for a video company, spend a lot of money and time to produce a popular on line game or spend same time and money to produce several popular single player games??