To be sure I don't tell it is worthless to buy a better camera. I just say you may want to improve your lighting first.
Most webcams including the ones in laptop can provide decent quality image if there is ample amount of good light on the subject.
A better camera will be able to better compensate for bad lighting, but that doesn’t make the lighting good, and good lighting will improve the results of both. That’s why pro mage capturers (photogs and camera crews) spend a lot of time on getting the lighting as good as possible.