All businesses have costs and revenues, aviation has always been high risk with regular large failures and investors have to accept those risks, you can make a lot of money when all goes well, if it goes wrong you loose the lot. Many national carriers are government controlled ( for better or worse) they will survive, for the rest the strongest will pick up after the crisis others will be taken over by new investors.
The number of passengers will return to normal with time, until then tough it out like the rest of businesses,