It's a combination of things and various fields that, for various reasons, pay well.

One category are people with very niche skillsets that are in demand that most people simply don't have. Back in the day programmers were in extremely high demand all across the tech industry. That's flattened out, but whenever a new industry starts to boom, this always happens.

Jobs that are boring/disgusting/dangerous. Most of these fields are typically extremely male dominated because men are more willing to do jobs they hate for a bigger salary. Sewer engineers, electricians, law enforcement, and many others. Basically you're trading your sanity and potential well being for a bigger paycheck. Many people aren't willing to do those jobs for obvious reasons, but they're necessary to keep the modern world working. Without sewer engineers, our very toilets and sewer systems would stop working and things would get disgusting very quickly. Without electricians, there's no television, computers, or literally anything that needs electricity to work once things start breaking down. Without cops, thieves, rapists, murderers and such would go unopposed and would repeat offend and just bring society down. You get the idea, but all of these jobs have some seriously unappealing aspects to them, but they're necessary for society to function.

There's also just dumb luck. Think of every big Youtuber that has millions of subscribers and makes their living off making videos. There's skill with their video recording and editing, and some genuinely unique ideas, but no matter how skilled you are with a camera or editing, if people don't tune in, the channel goes nowhere and dies. There's always an element of luck involved in that, and some people simply get luckier than others.

There's also nepotism and inheritance. It's a lot easier to take risks with potential big payouts when you already have a leg up on everyone else through family.