I am sure that if downloading the brain information into a hard drive will be possible, the rich majority will try to keep it for themselves. They will not want to have too many immortals out there.
That could be why you have never heard of it
Immortal might be a bit of a misnomer... The person could still die, like always... Just not death by old age... A bullet, or heart-attack could still be lethal
Though, I suppose if they did a nightly backup of their brain, they could have an emergency backup plan in case of death...
Fairly certain I saw a movie with this... the had these little dots under their eye-lids to show how many times they had been cloned already...
https://en.wikipedia.org/wiki/The_6th_Day
Now there is your time machine. You do yearly backup when you renew your driver's license. When you die, they'll restore your brain to the year you specified on driver license application. Or it could be a walk-in procedure, you walk in and do a refresh from 10 years ago.
Sort of like the movie Groundhog Day.
https://www.youtube.com/watch?v=6VF5P7qLaEQ
Combined with human cloning they will be able to backup one's brain when he/she is born and then clone him/her, grow him/her, and upload the backup. So people would never really die.