Industry, moving, and luck.

Using myself as an example. Software engineer in a town, 32k. Moving to either of the 2 nearest cities for the same role, 40-55k. Could go for management or to London too.

Doing a small Google search told me becoming a senior software engineer takes 6, 9 or 10 years. Starting at 18 you could be in a senior role in your late 20's.

Another industry-specific example. A friend of mine is training in London to become a cardiac clinical scientist. She'll be on 6 figures to start with. I can't do that in my industry before 30 without starting a company.

You might consider that a higher paying job might not stay that way. Your job sounds like it'll always be in demand and is relatively safe. There's value in that which is often overlooked.