Just an example: company I am working for hired several engineers in their early 30s with pay well over $100k a few years ago now we know that best of them is no more than barely OK, the most of them mediocre and few did a lot damage - and it has nothing to do with careless hiring we simply could not find anybody better.
So, if you are good it will be noticed pretty soon and you will make good money while having pretty interesting work (use #2,5,8 and 10 on this list as an example http://finance.yahoo.com/career-work/article/108648/25-top-paying-companies?mod=career-salary_negotiation).
If you are not so good, it usually takes years to be discovered by your coworkers and mangers and then there is a good chance that there will be nobody better around, the pay will be still pretty decent with interesting work and in the worst case you will have to move once in a few years when your professional problems will become apparent.
Just do not work for IT departments/services, IT has reverse reward scale: worse people get rewarded and the best ones go unnoticed and the absolute worst morons become IT managers - nothing could be done about it, it is the ingrained the nature of IT services, deviations from this common pattern are no more than deviations.