Is there an English idiom about describing the feelings of ones who work hard, get risk and finally achieved it but the others are being promoted and get all benefits as if they did it?
You could say that you've been left (out) in the cold or given the shaft because the others have taken the credit. You might even think of yourself as an unsung hero, although that term would be more likely applied to you by someone who discovers your contribution after the fact and tries to "correct the record".
Not an idiom but a proverb:
One beats the bush, and another catches the birds.
Explanation at proverbhunter:
One man does all the hard work, and another reaps the benefits. The reference is to the beater, whose job is to strike the bushes and rouse the birds or other game so that the sportsman with a gun can take a shot at them.