That rumor got started because a study in mice showed it lessened the severity of infection. The doses were very high, close to lethal. There is no evidence of prophylactic use making a difference. Only early stage of infection use. Some doctors are prescribing it for covid cases. It is not surprising it would work a little, it causes an increased immune response. There are also studies linking it to melanoma shrinkage. There is a large enough parasite burden in even a developed population that a twice yearly dose might make sense for humans.

All that said, buying an oral syringe with enough ivermectin to kill people with low body mass and trying to get your dose right is a horrible idea.