If people say playing chess is wasting tame, it's a bullshit, you should know that chess is sport game. I know many people still assuming that just a game, not a sport, but you know that chess it hard game because it use your energy, yaaa you are not using muscle but you are using your brain.
Alright back to the topic, if you want to be smart or thinking faster, you can improve your brain IQ by playing chess, some training will you get when you play chess are:
1. Think to the future:
yaaa this game use your math by counting what will be happen in the future, for an example what will be happen if you move your queen, or knight, so you counting that and you will get train your self to think about the future
2. Read the character of people
You can read you friend character by playing chess so how to do that.. it's very simple, you can read when your friend is playing, for an example you can read when they move, it carefully or careless, and still many patterns to read that.
3. Problem solver
Yaa when you playing chess you will solve your problem, so it also train you to solve your problem, and then you will be great problem solver in real life.
4. Thinking faster.
A true chess have limit time when you play chess, so it will require you to think faster as fast as possible, and only use your time in the important moment.
5. Avoid the mistake
Everyone has many mistake, so many people do not care about their mistake, but it really wrong and if you don't care with your mistake you will be fool, its because you don't know what the risk or effect by your mistake, in chess if you made a mistake you will see, the effect of your mistake immediately, so you don't have to do mistake when you play that. that why it also train your self by avoid a mistake.
So keep playing chess and be genius :-D