I've worked for investment managers my entire career and earned my CPA, but I have not worked in public accounting. In college, I majored in Business Administration with an emphasis in Finance and Management. My first job out of college was as an analyst at a Fund of Hedge Funds in the Investment Operations department. The IO team members were all expected to earn their CPA while working there. It took me about 18 months to study for and pass all 4 tests. From there, I was an active CPA even though I wasn't auditing publicly. I worked closely with our external auditors (from the Big 4) and the knowledge I gained while studying for my CPA was a tremendous help in my work load outside accounting.
After a few years at that firm, I went to work for a Hedge Fund as a Fund Accountant. My CPA was still active, yet not a requirement of my job. I do think having the CPA distinction helped me land this job and helped me get up to speed much quicker than someone who didn't have an accounting background.
I worked at the HF for a few years and then applied to PIMCO. In my current role at PIMCO, I don't use my CPA and have gone inactive. This just means I have not completed the continuing education requirements to remain active. Again, I do think my CPA distinction helped me to land the job at PIMCO and I still use many of the accounting skills I gained from prior positions in my everyday job.
As you see, you can use a CPA for a variety of different reasons, and you will always have the knowledge base to draw from in case you are faced with a difficult client question or business problem. As for pay, I'm not sure that I would have made less money without my CPA, but I do think it is helpful to have a meaningful license on your resume when an employer is looking at several candidates for an open position. The first company I worked for also paid for all of my study materials, review classes and testing fees, so it was a great opportunity for me to earn this license at very little cost to myself, other than studying time. A lot of companies will sponsor these costs and the big accounting firms do pay for your continuing education so you can remain active in your license.