Writing is hard, and there's nothing you can do about it

Writing well is hard because it's hard to get good feedback. Woodworking, filing paperwork, playing poker; these are all things that have relatively simple ways to quantify success. The chair doesn't collapse; last year's tax files are easy to find; you win more money than you lose.

Writing has a trap that other skills don't, which is that you can write for ten years and not get any better. If you're not getting good feedback about what readers think about your writing, you're going to be limited by your own ability to criticize your work; and by all accounts, humans are not good at analyzing their own writing. We always have blind spots, especially about things we created. Your tenth novel might be just as clichéd and boring and poorly-copy-edited as your first one.

If you can get 100 people to read your novel, and they're all strangers, and are all willing to give you good, solid feedback—congratulations, because you're a wizard or something. Most authors can only get a few people to give feedback, and usually those people are friends and family, because those are the only people who are willing to read a novel by an unpublished author. And their feedback is going to be biased, because they don't want to hurt your feelings if they think it's bad.