By entering a market as a big player, you effectively steal money from the existing players. Also, you're increasing the barriers of entry for new players.
Perhaps in a free, highly competitive market. But that doesn’t seem true in a state-controlled market like Chinese IT, where collaboration with the government is required. The CCP is free to pick winners and losers, intrude and interfere with little recourse for the companies who disagree with their decisions or end up on the wrong side of them.