There is a large gap between what is possible and what actually happens.

I recommend looking at EdLee's classic thread So.

It doesn't matter what I say. It's more important how the people who set these goals explain it to themselves. A number of them will say something the effect of "life got in the way," or, if they make a Freudian typo, "wife got in the way." This conveniently settles the cognitive dissonance between "I am smart" and "I suck at go."
At around that time he also felt there was not much he could do to improve, though he actually did.

assuming you work a few hours a week at it?

Look at the statistics on long-term weight loss. It's truly miserable. Do we then say that most people who are obese simply do not have the potential to lose weight? It is a lost cause? It would be interesting to see the numbers, but I wouldn't be surprised if people who have lost 30 lbs. or more (that they needed to lose) and kept it off for 10 years or more are rarer than 7 dans.

At around that time he also felt there was not much he could do to improve, though he actually did.

For me, I once thought a lifetime achievement would be to play in the Strong Player's room at a U.S. Go Congress. There some Congresses in the past where I think you could even make it in as an AGA 4d if you were lucky enough to be paired with with a 5d. Now, the bar is 7d and I believe this goal is impossible unless they change the rules again.

Today I don't know if I can get even a single stone stronger. (In fact, I have never known this.) If I can improve my reading ability, no problem. If I cannot, problem. Recently I have come to reflect on my games and realize there are things I am denying, though. Some low-hanging fruit that perhaps could add up to a stone even with no reading improvement. I also suspect that I read incorrectly, that the mental process is, in fact, wrong for anything above my level.

One reason it's hard to improve is that no one can see what's going on in your head. Imagine a golf player complaining that they haven't improved their handicap in years. They may be given advice such as "play more golf" or "watch these videos" or "talk to this pro" and then they say they have already done all those things. Later you get some magic glasses and realize that this player has been playing golf with a boomerang instead of a golf club all this time, and you realize there is a way to help. Without the magic glasses, no one will know about the boomerang and keep giving the same old, ineffective advice.

So it's possible I'm golfing with a boomerang. How would I know?

There is a large gap between what is possible and what actually happens.

I recommend looking at EdLee's classic thread So.

From what I understand, the research shows that it is basically impossible to lose weight and keep it off through sheer willpower. Many people try and they lose weight but gain it right back (and then some). So, yes. we do say it's a lost cause

Saying it is a lost cause is option #1.

Option #2 is doing something different than those people that have failed.

Whether you are actually willing to do option #2 is a different story.

That 6d comment was sarcastic.

Abssinica. June 17, 2014. "6d by 2015 or die"

Well isn't the equivalent of the "magic glasses" taking lessons with a pro and talking through your thinking process? That way the pro can look at what you're thinking and see if you're doing something completely wrong.

I'm assuming this was a list of people's real goals.

just to fly the flag for weight loss - I lost 2 stone a couple of years ago and have not put it all back on (just 1/2 a stone) - I'm not even that heavy. Defeatist attitudes just aren't helpful but for weight loss you need to change your habits long term.