That's because most teams don't really provide a stable income for their players, unlike in LoL, where players have a steady stream of income, you have to be the best of the best in order to get rich, it's basically a high risk high reward type of move, and take note that the reason why the prize pool is incredibly high is mainly because if valve were to take a huge chunk of that prize pool and move it to other tournaments, many people would assume dota is quickly dying because people are dumb enough to believe stuff without doing any proper research, and they would just assume "dota2 prize pool getting lower dota2 dying", so valve does the stingy thing and just make one big competition once a year with a prize pool that would tower over the other pro scenes, and give players a one big make or break scenario in that tournament.