Persistence is a big deal. I think part of why people dislike criticism is they don't want stuff to take very long or be much work. They don't want to deal with having to keep working on the problem. They just kinda wanna get it over with.
Criticisms are opportunities to make a change for the better and try again. That's not very appealing to someone who doesn't really want to try much.
Even if someone could deal with a criticism well, he also needs an interest in trying. People often give up after running into a couple problems they could have solved. They don't want to do the solving.
"omg i tried hard like twice this week. wasn't that enough? god i'm so tired of this trying stuff."
it's the same ppl who want a break when they achieve anything.
say you beat a level in a game, or finish a chunk of a comment, or check an item off their todo list. do you think more like:
1) "yay, that was awesome! now i can do another!"
2) "i did a lot. didn't i earn a break?"
the first attitude is persistent, the second isn't.
many people think a break is a good thing, to be earned and valued above trying, achieving, doing.
do you do stuff in order to have breaks? or do you take breaks in order to do more stuff?
People also have trouble with persistently pursuing chains of interests.
You're interested in and working on X, but you run into a problem. You think learning about or doing Y will help with the problem. Are you now interested in Y? Just as much as your interest in X, or less?
While working on Y, you run into another problem. You think doing W may help. It's not a guarantee, but it's your best guess about how to proceed with Y at this point, and if it doesn't work you have some other ideas too. You're not stuck, but you're not solving Y immediately either.
The more one is pursuing a chain of related interests, rather than directly working on the original interest, the less persistent people are. They lose some of their interest at each step in the chain.
People don't have much confidence in their ability to pursue longterm projects successfully. They find more problems come up than get solved. More links get added to the chain of interests than removed (they add T and V before finishing W). They get distracted by something else in life and never come back. Something happens. They aren't confident in doing related stuff and ever really coming back to X.
People who don't have a track record of success solving problems and making their projects work usually go for short term benefit or nothing. They can't do big projects. When there are many links in the chain of how to proceed, they stop. They aren't persistent. They should work on building up their ability to think and plan and succeed in a more organized, longer term and bigger way.
Here's a real example chain of interests of mine. I was interested in TCS (parenting and education philosophy). Unlike most interested people, I also studied Karl Popper, a philosopher who writes about how knowledge is created (more in a scientific progress context rather than how to teach, but it's still relevant).
Even more uncommonly, I studied William Godwin, a philosopher from around 1800 who had some similar ideas to TCS. To do this, I had to learn about how to read older English. The writing style is different. And I dealt with an issue, when reading some books, where 's' was written like 'f'.
To understand Godwin's philosophy better, I also read biographies about him. And biographies about his family. I found out about his career, his problems with debt, his marriages, the lives of his children, and so on. I read his daughter's book, Frankenstein.
Sometimes I had a specific problem I could solve this way. I didn't understand something and could look up the historical information. But a lot of it was just that I wanted to know more, understand better. And it worked.
Godwin's most important book, Political Justice, was primarily a standalone treatise. But it was also partly a response to the French Revolution and partly a reply to other books about the French Revolution. To better understand the context, I read Edmund Burke's Reflections on the Revolution in France and Thomas Paine's The Rights of Man. I liked Burke and read more of his works and biographies.
My persistent search for more information worked well for me. Some of it was interesting in its own right. Some helped me understand the original topics better. It led to new interests and it helped with the original interests. I like doing, so this was great for me.