Regarding figuring out my errors, I have tried. Usually it is that they aggressive players are not trying to make any territory. They just harass groups I have, and get their points from captures and the "holes" that creates. Often I have a group that end up running and it is 50% chance it gets killed and I lose. Surely they cannot read that out, they just gamble.

Just watch a few 6k-9k games on say IGS, and you'll see what I mean. Games where there are 100+ moves on one side of the board, and the other having one stone (and one totally unclaimed corner). Literally.

When starting to reach 10k level, there seems to be more and more hyper-aggressive players. They follow my stones and toss contact stones or invasive stones near virtually every stone I play.

What is a good way to learn to deal with that?

Those who say they have never, or rarely encountered these players - try visiting a local go salon (if you have them where you live). This is where I first encountered this style (and got crushed by nine old men who seemed to know no Joseki or no basic principles).

Playing on a real board also makes it less socially acceptable to try reading for several minutes. The pace is high and I am expected to respond within seconds.

I'll see if I can find some good examples of this style in my game archive.

Without seeing your game it's hard to say. But are you sure the invasions your opponent makes are unreasonable? I see many common beginner mistakes where they view their stones with greedy eyes, seeing "my moyo" and "my territory" when it's actually "my loose stones with many cutting points".

OP, I'm at the same level as you on IGS. I know and share your frustration. I lose to them as well at times, but I have found that developing my understanding of shapes has helped tremendously. I find that when I'm able to properly judge when a group is settled or know which attacking stones do not require a response, I can gain an advantage by playing elsewhere. The best source that I've found for this is Cho Chikun's All about Life and Death.

To the stronger players arguing some variant of "Your opponent could be playing a reasonable strategy." I don't think that this is what OP is talking about. Obviously, some games devolve (or evolve?) into fighting even at the pro level, and playing sharp moves can be good strategy. At our level, there seem to be two types of players -- players who are actively studying to improve and those who play the same strategy for years and stay at the same level. One of the main types of the latter are those who just try to kill everything. They are not playing some high-level strategy -- they are just good at fighting. Good enough to obviate the need for any larger understanding of the game at this level. Yes, we need to learn to handle these games, but OP is asking how to do that.

Actually I suspect they are better than you at the most basic of principles: count your liberties; your fancy joseki and strategic principles are no good if you run out of liberties!

Fresh game from today. Not the most typical one, but maybe enough to get the impression what I mean. Added some comments to it, and I see some of my mistakes.