I have been doing online courses and other similar tutorials for years and never paid for any of it or got any certificates.
I decided to do it for cs50. I have to say, physiologically working towards a certificate makes the course feel more 'real'. As though I am actually in the classes working under deadlines.
If I didn't choose the verified certificate I wouldn't be working as hard as I am. The consequence of not finishing on time would be physiologically less of a loss for me without the commitment of the verified certificate.
My advice as a former skeptic of paid certificates: If you have the money do it. But do it to push yourself towards a clear goal. Not for the piece of paper (if it is indeed paper).