FFS, that's called "fraud." Providing false information on a credit application is a criminal offense. Are you going to go to jail for it? Probably not, as long as you pay your bills. But it's 100% fraud and illegal and you can go to jail for it and people have.

Also, your accounts would be closed if they found out that you lied on your application. American Express, in particular, is known to conduct financial reviews and shut down accounts who can't prove their income.