I agree to @TheUltraElite. There are fixed matches but mostly in esports it's not the bookies that run it but it's the players themselves. For example, there were already a lot of players that were banned by valve due to match fixing. Knowing that Valve is the owner of steam where Dota 2 currently runs and the one that organizes huge tournaments with millions of prize pools, it's a devastating ban for life for those involved players.
https://liquipedia.net/dota2/Banned_players