I got my cert for two reasons: to prove to myself that I really did know the stuff, and to validate my credentials to prospective customers.

It's really the same thing as having a BS, MS, or PhD - you might not necessarily be any smarter, but it does show that you have the motivation to attempt & complete a particular course of study.

Slightly off-topic, when I was at Illinois Institute of Technology in the 70's the bookstore sold a bumper sticker: "Sicks munce ago I couldnt even spel 'engineer' and now I are one" it was quite popular 🙂