DotA 2 Will drain you of your will to keep playing, and yet you will always return.
DotA 2 Will make you regret ever playing it, and yet you will always think "Just one more game"
DotA 2 Will take away all your free time, and yet you'll almost feel proud of how many hours you have in DotA 2.
With the time you spend on this game, you could do all sorts. Study on learning a new set of skills to further your career. You could raise money for charity. You could be an aid worker for a foreign country and help improve the lives of others. You could even just play other games, you know, those ones sitting in your backlog, pushed aside by DotA 2.
But you won't.
You will always return to this game. The maximum you will learn from playing this game is how to insult others in various languages (mostly these languages will consist of Russian and Peruvian.). This game will become as much a part of your life as eating or blinking. Half the time you will not even remember having played DotA 2 on a certain day. It just becomes natural to you.
If you start playing this game, you will
You will also spend obscene amounts of money on cosmetics. A quick chest purchase here, a few random items on the market there, and boom. Like me you'll have spent far too much on a game which needs no money spent on it. If you start DotA 2, not only will you be subjecting yourself to a motivation-destroying hobby, but also subjecting yourself to a wallet emptying one too.
tl;dr This game will take away your time, money and patience for others. You will become an angry person.
Basically 10/10 GOTY All years