You can't expect to earn exponentially more if you sit in the same role for 10 years.
It depends on the company you work for.
I've been working at a company for 7 years and my salary increases were inflation related and I'm now earning a reasonable amount.
The problem I face now is that most companies pay far less than I'm currently being paid so when I move I may have to take a salary cut.
It looks like most companies pay senior system administrators/engineers between R25K and R30K per month (regardless of location, education and experience) which is a lot less than I'm currently earning.
Maybe it's time for me to look at another career path ...