True story
How many people think that; Chess is just a Total Waste of Time in Life!
I used to struggle with these thoughts too when I would find myself studying master games and techniques to improve my game for a tournament or rating. I just came to the conclusion that If chess makes you happy and it doesn't interfere with your priorities than keep enjoying the game.
I personally try to keep my study down to about an hour a day visiting sites like chess.com, chesstempo.com, chessbounty.com, etc. Just my two cents.

A related question: Can studying chess be a waste of time? If so, when? And for whom?
My personal answer is yes, it's a waste of my time to study. Because I play for fun and sociability, and I do Not like studying. .... any more.... I declared out loud on the day I got my doctoral degree that Nobody could Ever make me study again! ... not even Me. (and I've stuck to my resolve. .... teehee)

i started playing chess because sometimes you get bored with tv series playstation and sport in your free time what else is there to do in life

Kindly define “waste”.
Case in point: once in a while, I play online chess with my son who lives thousand of miles away from home; and we enjoy the bonding time. I consider our chess then as “productive” time.

There are bigger wastes of time like drinking, drugs and gambling. I think chess can help instill confidence under pressure, problem solving abilities. It *can* but not always will depending on how you treat it.

yes , I played competitively and achieved master status 16 years of studying and play got me divorced, broke, trophies and very little money. I don't even have any friends left but 1 who moved away. So say what u want , I think chess helped ruin my life. Even when I played well and beat senior masters the others would make excuses for them and when I lost no excuses were offered nor any credit for my brilliancies on wins. I also found hi rated players to be the biggest cheats because when you are winning they will try to win by distracting you with BS like coughing in your face and purposely knocking over the pieces and clock if you are short of time. Also I had a 2400 player(russian) touch a piece and refuse to move it, good thing I had a witness because he was a GOM of the club and the director was going to take the 2400 players word denying the cheat. Most players arent strong enough to see what these "strong" players are made of but if you can put their back against the wall - perhaps you will see for yourself. I wasted alot of time becoming a good player to find i shouldve concentrated on the art of cheating. I still manged to beat these players on occasion so its not "sore loser" if that is your idea. I was also a city champion twice and a first board at college. I was 18th at the US open one year (the only year I played) and then , after the TD messed with me about some minor rule and threatened to take my hard earned points away, I lost my energy and could not recover, losing three in a row and droppping out. A tragedy fo me for I wasplaying so well before BG messed with my head. I was able to keep my points but the stress was too much on top of the competition and travelling so far to play. You may take a guess who BG is. I had a long term goal of making the olympiad team.
This is somehow a tragic story!
I think some of us feel the same as you in the sense that we are afraid of investing so much in the game to have little return. At the moment I enjoy playing and studying, but always with the feeling that I should once stop the whole thing and begin to invest my time in other, more productive things.
If chess is a waste of time then why r u downloaded it it?you just waste 10 sec of your life waiting for it