High paying job

I got 6s and 5s in my gcse is it possible for me to get a high paying job i am doing business studies pschology and maths for a levels i just want to know whether i messed up or if its possible i to have a high paying job or if it will be a lot lot harder because of it.

Your future salary has no relevance to your GCSEs. It's going to be dependent on how good you are at your job and what sector you choose to work in.

Zero correlation nor causation...?

Depends on the person and myriad other factors. But there's a thing called the 'mid-life crisis' for a reason, some people determine a route they are unsuited to and can't hold it down, and almost everybody changes in life. There's a big, though unspoken, assumption that at the point you leave childhood/formal education you are fixed as a person. In fact you continue to grow and change through life, you learn and experience outside any formal framework, and inevitably you change. One near universal change is that time becomes more precious, and you don't want to waste it. Slogging away at a job you don't enjoy is something many, many people who find themselves in that position, decide they have to stop.

Additionaly, I have met people (and include myself) as someone who had a very firm conviction of a vocational career path, pursued it successfully, but then lost that vocation and completely changed careers (see mid-life crisis!). Once my feeling of vocation was gone, so was my commitment, they were connected, and so I wasn't going to progress. However, I have continued to progress in my second career, and at a similar rate to my successful peers in my original career. My initial career choice wasn't necessarily wrong, I just changed.

I'm at the latter end of my career, and I've worked in several sectors where there is a lot of publicly recognised success. I've never met anyone who was both right at the top of the earning range AND didn't adore their job.