The anecdote about taking 50k IU of vitamin D is really dangerous. Above 4000 daily IU is already putting a lot of people in hypervitaminosis (https://pubmed.ncbi.nlm.nih.gov/21646368/)
Yeah, that's a very high dose. It's true most of us are deficient in vitamin D, but it's the kind of thing that should probably be regularly monitored once supplementation starts, rather than popping pills and hoping for the best.