That's the correct mindset if you want to improve. Trust me most 6k players felt the same way. If they think they're good enough they won't achieve that 6k. The better you get the more you realize that you're lacking. Once you think you're good enough, you will grow complacent and stop improving. You will always find excuses to shift the blame to others instead of focusing and looking at your own mistakes.

Edit:

I think talent and effort alone is not enough to be the best. You need luck and connection too. For me, my luck came 3 years ago when i met Jon, now captain of Insidious Idol, in pub game. I added and talked to him. Later he always invite me to play party with his friends. I learned a lot from him, but what impressed me the most was his attitude. I remember when we were 0-10 down, he calmly said "relax, its fine". That was the first time i met someone like that after years playing dota, from my g-arena days until dota 2.

Had i not met him, i'll be like your average assholes in sea server. Blame others all day in pub and never improve. Just like in life, the people you meet will shape who you are. If i ever achieve success in dota in the future, i owe it to him.
I don't play party but you can add me. Tell me who you are or just say you're from lowyat in my steam profile page. Any forumers who want to add me can do the same. I need to keep my friends list clean. Too many friend request after solo rmm game.

Now that i think about it, i can make more pictures like that to explain support roles.

For that purpose, I need a larger version of this. Google has failed me, or maybe i'm just too lazy.
http://i.imgur.com/Sw79q.jpg