The entire concept of going to work for someone else is that it's supposed to save you a lot of trouble having to sell your services on your own/run your own business. If it has become so much more profitable for doctors to leave and start their own practice then they should be doing that because you're not paying them enough! You're not "making good" on your end of the bargain that we offer in civilized society.
That line of reasoning goes both way. If you sign something, then it was worth it for you.
It depends. Many instruments, such as PET in nuclear medicine, cost a lot. One have to work for hospitals/networks to help his/her patients with that instruments, no matter how good he/her is.
Also, if the doctor's patients all like him enough to switch to his private practice when he leaves then clearly they weren't paying the doctor enough. He was worth that many patients!
Can't stress this enough. Show up, attend to patients as scheduled then go home and enjoy life. All the boring details are taken care of. It's definitely more profitable to start one's own practice but the comfort of working at such places should not be underestimated.