Also startup accelerators usually work with businesses that already exist. It's actually a good analogy. If you already know a little bit about coding and computer science a bootcamp can really help. If you don't have the drive to learn programming than a bootcamp can leave you with a huge skills gap.
My first business failed miserably. I had no business training and no one in my family who'd ever run a business. I was just overwhelmed all the time and never had advisors to reach out to (a problem YC students wouldn't have)
In hindsight, I know what I did wrong and what I should have done instead.
I'd say it took me at least a year of failing before I could gather my bearings and understand what was going on.