Then they saw how performant, long battery lasting and cool their iPad (ARM chip) was.
This became an easy decision for Apple to ditch Intel when they saw how much better their own iPad Pro was relative to the 12” Intel MacBook.
For those who have being using Mac since the PowerPC days all have used this argument against X86 chips. As you all know, Apple actually had to switched from RISC chips to Intel X86 chips, before they switched back to ISAs chips now. Just saying performance is not the main reason to switch chip sets.