The answer is, simply, crowdfunding.
With every International since 2013, Valve has released a companion guide alongside it, an in-game app called the Compendium. The first iteration cost $10, and 25 percent of the profits went towards that year’s International prize pool. It offered a few goodies, like a new courier, heads-up display, and cosmetic skin for a hero to wear in-game
Full detail and credit
https://compete.kotaku.com/how-exactly-does-dota-2-come-up-with-over-20-million-i-1796879005
The answer is, simply, crowdfunding. With every International since 2013, Valve has released a companion guide alongside it, an in-game app called the Compendium. The first iteration cost $10, and 25 percent of the profits went towards that year’s International prize pool. It offered a few goodies, like a new courier, heads-up display, and cosmetic skin for a hero to wear in-game Full detail and credit https://compete.kotaku.com/how-exactly-does-dota-2-come-up-with-over-20-million-i-1796879005