when should you give up

I'd say you should give up immediately, before you get even more involved in this thing we call "chess," when in reality it translates to "mess," bc chess is a mess. 

When to give up? Whenever you would feel happy about your life without any Chess in it.

When not to give up? Whenever you would miss Chess significantly and benefit a lot from participating in it.

It's up to you to decide. Don't play Chess to be the champion, accept that natural talent is a barrier, that some nerds (not an insult) have the time to spend relentlessly studying the game while you have other life priorities potentially and so many other factors.

We all have our specialties and shortfalls in life. Chess may simply not be (or may well be) your calling, don't force it either way.

@loudomvis, do you remember those guys that could never really play StreetFighter or MortalKombat all too well - they just sort of stuck around on the sidelines at the arcade - until one day a new friend came around and noticed, and basically said to them, "you're doing it wrong"?

The same goes for chess.

game is destroing, when you start playing vs real people it feels like you are the most stupid in the world.

If you are happy keep on playing even you are not improving. If playing chess means nothing to you then stop playing it a lot. 

I never do because people sometimes to promote pawns forget to check and you end up drawing. I am respectful, I don't waste your time, but I never give up.

Yep!  I was one of those guys.  LOL!!

Lol. There has never been and will never be a Septillion non-grandmasters but your point is valid on enjoyment of the game; that comes first. I'll take it further by saying that the struggle IS the joy. I am just over 1200 after decades and hundreds of thousands of puzzles/tactics. I get it, I'm not a great player. Yeah, it is what it is. I can now perform tactics at the 2000+ level and my endgame knowledge is better than many... I'm only just now learning that I have to work on controlling my openings to gain the advantage to even have the opportunity to put all other skills gained to use. It's not work for me; It's a pleasure. If you can embrace the difficulty, its a pleasure. 

I think 1200 is serious player. Yeah, of course it would be beginner compared to titled players but it was my first serious goal to achieve and I had to know some basics in tactics. So I think 1200 is good. You will be god to all your friends that just play for fun

If you aren't enjoying the game approach it differently. You have to realise improvement doesn't come quick, you have to be very patient. You can spend a whole month studying the game and only improve slightly or even play a bit worse because you are burned out from the game, but know that the improvement will come. Just take a break if you aren't enjoying the game.

You have only played 300 games. But just make sure you analyse them and try to find something to remember from every game.