"what did i do wrong?"
It is hard to say. /dev/tty* devices have a variety of configurations and there are a lot of them.
/dev/tty1 should be root root 600 Major=4 Minor=1
/dev/tty2 should be root root 600 Major=4 Minor=2
/dev/tty9 should be root root 600 Major=4 Minor=9
Then the rest of the /dev/tty* fall into three types although each has a unique Major and Minor number.
root tty 660
root tty 640
root uucp 660
So use another Linux OS to check the /dev files in the LFS partition to see if the ownership and permissions are reasonable.
"unable to change tty /dev/tty1: Read-only filesystem"
It is also possible that you booted into a read only / filesystem. Check /etc/fstab and your bootloader parameters.
Be prepared. Create a LifeBoat CD.