I used to do both as well, work as a corporate lackey and trade on the side. Being a longer term swing-type trader works best in that situation, so you're not a tick hound. But like someone said earlier, to be truly successful in almost anything, you have to give it your full attention and dedication. Sure you can do both for a while and be modestly successful. But after a few years you begin to realize that you're not making the best of either side.
You can't give 110% efffort to trading/investing because of job responsiblities, which distracts you from focusing on profitable research, opportunities and ideas; even just reading a good book to stimulate some thoughts. You also can't give 110% effort to your corporate job because you seem to always want to do something stock market-related during your free time (conduct reseach, check quotes, look at charts, getting away from coworkers, etc, etc). So you also get distracted from striving to get promotions, to get noticed, accepting more responsibilities; the little things you need to do to work your way up the ladder with bigger salaries.
I finally realized I was really screwing myself over both ways. Like I said, it does work for a while... and if you're single with only yourself to worry about, you do end up saving a lot. But you're not great on either side of the fence. Just average, maybe above average, but still mediocre either way. And by the time I knew it, my twenties were gone. Time is the most valuable commodity in one's life. Health too. So always being stressed for time doing two jobs at once can't be good.
So it depends on each individual's situation and circumstances, which are countless. Not to mention one's unique mindset/personality. I finally chose to jump off the fence. But still young enough to jump back over again should things not work out though. ALWAYS HAVE A BACKUP PLAN.
