There are several reasons that come to mind: 1. IP ownership - many companies include total IP ownership during your time of employment. 2. If it's a soul suc

There are several reasons that come to mind: 1. IP ownership - many companies include total IP ownership during your time of employment. 2. If it's a soul sucking place, you'll burn out quickly and won't want to touch a computer, even if you love coding. 3. Making some company 10-20x your salary is disheartening. 4. You are at the whim of your bosses. 5. Many companies make getting anything done a huge pain in the ass. Over zealous security policies, over tight virus scanners choking your development box, requiring shitty company hardware to develop on, some DBA rejecting your SQL because he decided everyone should do it this way this week, network guys not fixing a horribly slow network, etc. There are advantages, of course. The problem is you probably will never be able to get a business up and running while working at another job, it just takes too much attention.