You seem to be one of the more outspoken critics of CTS. It seems like every day or two, something about the game has you upset. Why don't you save yourself some stress, and quit playing? It doesn't sound like you're having any fun anyway, and that is supposed to be the object of the game. Have fun!
I have over 50 billion in hunter bucks, but that hasn't happened to me. There are others with over 100 billion that haven't had any problems as far as I know.
Play the game on your own merits, and don't rely on ways to cheat. If you are a lousy player, and can't accumulate coins, then maybe you should play something else. Many of us longtime players have earned millions of coins by just playing and getting better at it. Try it sometime.
You should check out the DH 2016 forum. There must be a dozen of them that were posted today. They're all in a foreign language, so I'm not sure if it's porn or what.
That's all there is. When you upgrade your weapon, you make a choice as to what part is upgraded. The sight is one of the choices. Others are, fire rate, suppression, and others I don't remember right now. You have to decide which part you want to upgrade.