> Why does someone have a de-facto monopoly in some markets?
In this case, and in the case of any disaster, that question has an answer, and there’s no problem that a government or anyone can solve. People who happened to make masks and sanitizers, or happened have them in stock, by luck, suddenly became de-facto monopolies. And it will just as suddenly go away.
> When competition exists, the prices will fall to appropriate levels to correctly distribute the emergency good.
In this case, and in the case of any disaster, new competition cannot appear fast enough to meet the demand before the demand goes away. The demand is inherently unstable. Even if competition arrives, the demand will drop, so someone’s going out of business. This free market belief that things will settle at the right place depends on the assumption that there’s infinite time for the market to settle, it doesn’t really address the fact that without some regulation you can sometimes end up in situations where both producers and consumers lose, where there is only economic loss. If the demand changes too quickly, price gouging costs consumers, too many people got sick from lack of supplies due to price gouging, suppliers ramp up production only to have demand vanish, and they suffer loss of demand at the same time they’re stuck with warehouses of oversupply. Sometimes nobody wins if there’s nothing to hold back reactionary behavior.