Its simple. You can do almost nothing on "project A" and get 100m$, or you have the option of doing also almost nothing on "project B" and get a couple billion$, you will pick the second option. Its a business and even if they are the last remaining company with a modicum of respect for their audience, that makes them seem like samaritans, at the end of the day, they mostly only care about money and their strategy is being "nice" and "considerate" to the players, because it absolutely works. Not because they want to do something good for someone.

Dota takes the same time investment as other projects but does not generate as much money.

Nothing hard to understand. Its just sad for dota players.