Businesses (including many of those demanding bailouts) have spent unprecedented amounts of money on stock buybacks in the last decade. If citizens are expected to have a reserve fund to handle unexpected crises, so should businesses.
The alternative seems to be to let millions get sick en masse, potentially leading to similar shutdowns for longer time periods (i.e. failing to "flatten the curve"). I don't think you can claim those businesses would be fine unless you define a timeline to go with your assertion; say, "those businesses would be fine for n weeks."
Remember that sick != dead, unless you have risk factors, 60+ or is immunocompromised in which case you should do everything you can to stay at home and practice distancing.
The other thing is that half of the cost is in the form of low interest loans and loan guarantees, and presumably most of those will not default if this doesn’t go on too long and thus won’t actually be real costs
These aren’t the same. This shutdown (however justified) is because of the govt. If the government demands you shut down your business, or that you can’t go to work, you deserve to be compensated for that. If the government hadn’t mandated it, young people would still be out working and spending. Those businesses would be fine. If the govt wants to shut everything down, they have to pay people for it.