80% of what? There are 85,000 H1B visas per year, and vastly more job postings (and hirings of citizens) each year.
Needless to say, that doesn't make any sense.
You're right that I shouldn't have said 80%, but this still implies almost half of all job postings are ghost jobs from companies trying to hire H1-B visa workers.
It's still an insane claim.