I think aim is one of those things that has physical limiting factors. Some people have unearthly hand-eye coordination. Everyone can develop such things to a point, but I think you reach a ceiling.
If your ceiling is low you can try other things to compensate such as improving jumping, learning lining spots, learning how to evade better, but you will always have a handicap against the best players, because they can do all those things AND aim.
You get better with practice. But to use an analogy, a 5',1" point guard may practice all day long and he won't be a 6',1" point guard. He has limiting factors. There have been a few really short point guards in the NBA, but not a lot of them. There is just too much to overcome.
In the same way if you have naturally poor hand-eye coordination you can build up to your potential--but that is it. You will probably never make the big-leagues so to speak.
Those who are learning the basics of the game(understanding of most maps, strafe jumping, picking up on lining concepts etc.) will progress rapidly. Then they start to hit their ceiling. They progress more slowly, if at all, and become discouraged. Your problem may be expectations. I think there comes a time when there is only so much you can do.
And once you get to your ceiling, don't be surprised if it is not at the top of the heap. Hence the temptation for those who are just a bit lower down to want that edge through hacking.
Just admit you are not as good, and enjoy the game. Or quit. Most people will never be Michael Jordan or anywhere close. But they can still enjoy a pick-up game. And most will never be fatal1ty or however he spells it, or even Bix, Olbaid, Super, Moe, Blitz, Dystro or whoever folks consider to be good at DP. But they can still enjoy a video game.