No, it is not harmful or bad to secure erase an SSD.
The only thing that could be called slightly harmful is that a secure erase is the same as using one full program/erase cycle on all the NAND in the SSD. That is a extremely tiny loss of the NAND's life span, and not at all worth worrying about. The concern over wearing out the NAND in SSDs has been found to be very exaggerated.
Normally it is unnecessary to secure erase a SSD often or at all, a simple Windows quick format will be enough to start over again.
Any reason you need to secure erase your SSDs a lot?
I'm sorry, but I'm to lazy to Google that for you...