I'm more than happy to share!
I'll speak in terms of my experience rather than in terms of other developers unless I think of a common trait which I've seen.
When it comes to improving one's craft as a web developer, I noticed that some are lucky enough to get around some really experienced people, and they absorb knowledge from those guys. But I don't see them reading from the wealth of literature that exists in this field. Code Complete 2, Head First Design Patterns, Clean Code...etc or classics like "Structure and Interpretation of Computer Programs". Pursuing this kind of knowledge continuously, while not exactly a high value set of things to read as someone who's just trying to pump out a quick MVP, are hallmarks of a really really good developer. They think differently, see patterns that other developers can't see. They constantly improve their code to be readable by anyone, and write it so that it's harder to break and easy to extend. So to answer your question, one problem they face is a lack of continuous learning or reading, not from the 10 billion free resources or $10/mo videos that teach the shiny cool new thing.. but the fundamentals and the things that the very best in this field have put out.
Another problem I encounter myself is finding other technical entrepreneurs to talk to on a regular basis. I was thinking about creating a mastermind of tech entrepreneurs who meet twice a month to share where they're at and allow everyone else to brainstorm solutions. There is Indiehackers but it's not the same to ask a forum question vs asking a group of 8-10 people on video chat and being able to share screen and all that.
The tech world is full of info on startups, these people who want to solve some unique problem and raise a bunch of money to get paid to solve it. That's not me. I want to build a business, wether it's a unique problem or not doesn't matter to me, what matters to me is if I can compete well enough to be profitable, grow, and build it either by myself or with one other dev max, while also making sure we've got a solid marketer to guide product development, ad copy..etc
Finding jobs in places where there doesn't seem to be many jobs. I'm a RoR developer, and in Florida, there aren't that many Rails positions around. I noticed that the recruiters have no idea how our craft really works, and many times you only figure this out when you meet the company face to face.
Having a clear path to go from zero to a seriously top notch developer. Like if there were a course that could take me from 0 to world-class status in terms of development in like a year, and I'd have to take out a load of like $20k to do it, I'd have done that in the very beginning. It took tons of client work, eating pinto beans and rice in California living out of my brother's efficiency, and like 80+ hours a week of mind numbing
effort over the course of 8 months to build up enough of a portfolio and experience to finally land a contract job that made the quality of my life finally not be misery while still being able to get ahead.
As a freelancer, I wish I'd have known about or found a clear path to a mentor who could PERSONALLY show me, or at least through a group setting, how to do all the things a *really* successful freelancer does to go from 0 to $100/hr as a freelance developer. I did buy the Double Your Freelancing program but for some reason I wasn't able to get that working for myself. A coach could have identified the exact thing I'm confused about and bridged that gap, something a book can never do. Same idea, like the one about development schooling, if I could purchase this kind of hands on, spot-my-blind-spots-where-they're-at, type of treatment in order to save a ton of time, I would have. When you're in that scarcity state of mind, alone, and, just grinding so hard you gotta go for daily runs like clockwork to blow off physical steam, it's hard to see or think creatively enough. It was like that for me anyway.