Trading can be the main source of income which will provide you with the high-quality of life but it is really hard to achieve.
There are lots of traders who don't do any other jobs except for trading, but in most of the cases they work for some funds where they manage the money or banks. As for individual traders, there are a few of them. I believe that trading is too stressful to do it for a very long time like 40 years. In most of the cases traders earn some capital, so that they will be able to learn on investing rather than trading. Just imagine what you will turn into after several decades of years of trading full of stress and uncertainty. More than that, I don't really see fit in that. Perhaps, you know about the bet between Warren Buffet and some trader which was all about determining who would earn more. It turned out that Buffet earned more having the same budget as a trader but he earned the money even more passively. So, the question is why should you work more if you will earn the same amount of money?
I think that trading should be considered to be the first step in investing and financial freedom. Trading is nice because you can earn some decent amount of money in quite tight deadlines, but in the long run such an activity is more stressful rather than lucrative.