It's too late for me to start again at the bottom now but I'd like to advise my DC what sort of career to look for.
It's hard to advise on career itself, without knowing them, but there are more general principles ...
Potential to earn big is better in private sector
Focus on industries where there's a lot of money around. Finance is a constant here, insurance, things like that. Tech is one at the minute, but it may wane a bit. What services will we really need in 10/15 years time?
Keep building skills that there is clear demand for. As opportunities arise to specialise, go for things that are up and coming, or the more dull or complex stuff that others can't be bothered with.
Identify more senior people who have their sights on the top and cultivate relationships. As these people move up, they'll want to build teams around them.
Be prepared to move roles to advance.
If they have the personality to succeed in a sales role, that's always a path with potential. If you can sell, you're always able to demonstrate your worth to the company in a very tangible way. Sales is a very broad church btw, includes professional services and things like that.
The working hard bit is a red herring. Virtually everyone who earns big will have worked very hard for some part of their career to get there.
But becoming more senior and earning well has lots of advantages in terms of setting your own terms/schedule, dropping days, doing consultancy rather than standard employment.