You're... -sigh- I'm trying to figure out how to answer this for you. I've held my own on lan in 1.6 against... many of the people you're seeing playing professionally in CS:GO today (mostly talking Euros here), placed at many a CPL, and won a lot of US lans. - from 2005-2011ish.
Let me put it to you this way, okay? My team - and anyone on it who actively played on the lan roster - could simply destroy anyone else in the world - when you're talking about out shooting, out fragging.
Truth is? It really doesn't fucking matter. I know... off my friends list alone - at least 10+ people who have never made it out of LEM who have some of the most insane amazing reactions and aim - AND they get the RNG to land in their favor, often.
Some of the -best- players I have ever seen in the "professional" scene here in GO... quite simply, don't aim well. When you're talking about aim in itself. Raw, nothing but mouse to head movement like the notorious "INHUMAN REACTIONS" shot Hiko got recently. YOU DON'T NEED THAT. It's... so unrelated to playing the game so far outclassing everyone else that it's essentially pointless.
If you keep your crosshair at the right place at the right time, move your mouse the right way while firing, and have even a sub-average reaction time (say, 300ms)... you win 95% of the time you engage. Even at the professional level. When pro's rush a site dry when the opposing team has flashes, etc (THIS RARELY HAPPENS, BUT BARE WITH ME)- you can see what happens when the opposing team still has their view at the proper place. The entire team is mowed down, almost exclusively.
The -biggest- part of the game, hands down - is using grenades, flashbangs, smokes (And Mollys now) to manipulate your opponent into not having himself set. Or your teamates. They frag your teamate, you have a small window they're no longer "set" in. Or ANYTHING else you can do to get the opposition to not be "set".
Think of it as... melee combat, medieval style. Anyone holding an angle is a guy with a pike set against a charge. Any time he has his pike set at the proper place, the thing charging is dead, period. Get him to move his pike for any reason, and he's yours.
The -very- best of the pros? The ones who win, consistently - are those who have mastered getting set fastest, and being set when the enemy doesn't expect you to be set, etc. - while being a master of throwing the opposition off of their own set.
Most globals don't understand the strategy aspect on an individual level of Counter-Strike. It's been like this since 1999, and its what keeps a LOT of us coming back. It's like motherfucking chess with guns.
And even then, this is me grossly over simplifying a complex topic that quite frankly... I don't think anyone has "mastered" yet, the way people have mastered chess. And they probably never will - Chess had centuries. CS has had less than 20 years.