Yes and no. Yes if you're talking about having a chance of working in the US at the level lots of PhDs do (faculty at a university, principal investigator of a

Yes and no. Yes if you're talking about having a chance of working in the US at the level lots of PhDs do (faculty at a university, principal investigator of a grant-funded project, etc.). No if you're just asking if you need a PhD to think and work independently at the level of a PhD in a given field. It's my understanding that Freeman Dyson does not have a PhD, for example. He's also a bad example, because he's Freeman Dyson, and most people are not. Outliers are often bad examples. I think it's still a good idea to go to finish college, although dropping out worked for Bill Gates and Steve Jobs.