Currently there are several aspects of chip decryption:
Reproduction of other people's circuits, decryption of the chip to get the program made by others, you can make an electronic product like others.
Access to some confidential algorithms, the purpose with 1 is also similar, that is, more advanced rehash.
Decrypting someone's bank card chip to get information about someone else's bank card, you know the drill.
Decrypting the chip to get higher user permissions to do you-know-what.
Of course some people also decrypt the chip in order to prove their level and have fun.