Second try for PhD after failing comprehensive exam Two years ago I failed my comprehensive exam at the US PhD program, although my advisor was happy with my results. Then, I started to work at one of the top companies, but, I have never ever given up my desire to finish a PhD.
I want to apply to PhD programs again. How should I address the issue of failing my comprehensive exams? Basically how to convince them that you are able to finish their program.
It certainly is possible; I too have anecdotal experience.
There's really two main items at question here.

Why did you fail your qualifying exams the first time?
What will you get out of completing a PhD?

My experiences are as follows -
First, I failed because I took them too early and was not professional about my studies as I should have been, plain and simple. At that point, I was locked into a rigid timeline for a retake which I attempted to negotiate with the department. They pushed back and I passed 2/3 retakes, but that was not enough. I did great research, my advisor totally had my back (and is still incredibly disappointed with the department and the handling of my situation), the only reason I didn't continue was because I did not pass the qualifiers.
Based on the fact that you are at a 'Big 4' consulting firm, you probably  have a good career ahead of you. I was in industry for a while before returning to academia after undergrad, so I totally understand that academia provides truly unique opportunities. For me, it allowed me to re-orient myself from a management career track to a technical career track. And in the process, I fell in love with the process of finding research problems and having the freedom to really dig in and become an expert. Academia is really the only way for me to pursue the topic that I want to pursue, and to continue to develop myself as an independent researcher.
You really need to think hard about both of these questions. I did, and I knew that I wanted to continue. I worked hard to develop a relationship with another PI. And honestly, I'm working on problems which are more interesting to me in a niche field that is on the cusp of some very interesting results at the intersection of theoretical results and application.
There was another member of my cohort who didn't pass the qualifiers in the same round. They already had a master's, and decided that getting a PhD just wasn't in the cards for them.

On the practical side of things, you're giving up 3-5 years of, I am guessing, a 6-figure salary with good retirement package. That's a LOT of money, not to mention bonuses, raises, etc.. On the other hand, the golden handcuffs are likely not too tight on you yet, so now would be the time to take them off without too much pain.
In the end, this all really falls on you and how much you want to get the PhD - at this point, I would say it's not just want, it's how much you need to get it, for personal or professional reasons. There's plenty of ways to work on interesting projects doing what you want to do without a PhD. My biggest recommendation: exhaust those options before jumping back in.