Generally I'd say you should study as much as you can in the early years since it's much easier. It gets a lot harder to get back to books and exams as the years pile on

Can't you do one year, get your A, then try for B if you still feel up for it and if it doesn't work out, get a job and try again later ?

There's nothing wrong with starting work at an early age with few qualifications, many are very happy in life (rich or not) that way, but, if you are even partially academically minded, I would stick with it as long as poss, rather than give up because there's easy money in work, etc...

The couple of years you have to give up now will pay off the future