CS:GO has been on the market for a while. There have been a lot of new, good, free games that have come out since CS:GO was released. They had to make it free in order to "revive" the game as the players were getting bored with it and moving on to these other games that were being released all the time. Since Valve doesn't want to release Half-Life 3, people were losing interest in most of their games. The competitve scene in CS:GO is mostly on third-party apps such as ESEA and FaceIt. They provide much better anti-cheats and allow for higher tick rate servers. They are trying to keep the game alive for as long as possible in order to stay sort of relevant in the gaming industry, to be know for things other than just Steam and Half-Life.