Do I still need a PhD to do research if I have double honours in CS and Pure Math? I'm planning to get double honours in CS and Pure Math. I'm confused what's the biggest benefit of Ph.D. will be for me? People say you learn to do research, but I can do research(as I have the appropriate background, CS and Math) sitting at home or in industry. Then what's the biggest benefit of Ph.D.? Why should I do Ph.D.?

EDIT1: The only thing that is stopping me from getting a PhD is time.

EDIT2: Link to my new post.
I can do research sitting at home


Read a few research papers published in highly regarded venues in your field of interest. Are you capable of producing that kind of work at this point in your training? 


Do you know how to identify important and original research questions? 
Do you know how to select an appropriate methodology for answering a particular research question? 
Do you have a "toolbox" of methods you can apply to different research questions as appropriate? 
Are you able to critically evaluate your own and others' work as experts in the field would?


If not: a PhD is an apprenticeship in which you learn how to do the things mentioned above under the guidance of an expert advisor, in an environment that is designed for learning those skills, hopefully with a salary that allows you to focus on improving your research abilities.