Highly unlikely people are misdiagnosed and parasites can be very hardy and can outlive us. How can people be sure you're not just trying to talk a good game when you sell these for a living:
"ParaZapper - Hulda Clark Zapper for Parasites"
Btw, saying so many people here struggle to get rid of parasites is kinda saying your product sucks.
And if the proof is in the poo and it's so easy to see with one's eye amongst all the muck in the toilet, trained professional doctors and lab technicians with powerful microscope would have an even easier time spotting them, yet when all these people take samples to an MD or do a stool test, hardly anyone here can get them confirmed. All the evidence points that the proof in the pudding was a misdiagnosis.