Asking a professor whether you should pursue a Ph.D. is a little like asking The Rock — aka Dwayne Douglas Johnson, the world’s highest-paid actor last year — whether you should become an actor.
Once you enter a doctoral program, the main problem isn’t necessarily that you can’t finish. I know very few people who left graduate school because they weren’t smart enough to finish — it happens, but it’s rare. More often people leave because they just decide getting a Ph.D. isn’t for them. The truth is: It’s very difficult to understand what academic life is like until you actually try it, and lots of people try it and decide it’s not a good fit.
This, then, is why you should be wary of any advice you receive from professors about graduate school: It’s coming entirely from people who decided that academe was a good fit for them.