There are many reasons for professionals, even the most established ones, to become certified by the Python Institute. The IT industry is, and always has been, in a state of rapid change. What is relevant today may not be relevant tomorrow. Python is a constantly evolving language, and it's important to be up to date on the latest developments at all times.
PCAP™ and PCPP1™ certifications allow you to demonstrate that not only are you up to date, but that you can competently deal with Python-related issues. Python Institute's certification enables you to keep your skills up to date, and to show others that your skills are up to date.
Furthermore, with the Python Institute, you gain access to a large network of Python professionals, a valuable resource for solving programming challenges, and for developing innovative solutions.