Problem is, profiting off of other people’s misfortune and lack of choices, while following an economic logic that might lead to a more efficient distribution of resources (assuming a model of elastic supply and competition), is also morally reprehensible to non libertarians i.e. normal people. 

Most of your fellow citizens think it’s gross to 1. ration scarce necessities in a way that guarantees only rich people get them and 2. greedily take advantage of others’ desperation to benefit themselves. 

If you want to defend the most selfish, soulless manifestations of the “free market”, go ahead

But consider that group chats are filled with information about charity, donations, volunteering and mutual aid, not auctions  - because most people are not predatory ghouls.