agriculture is the reason there were 2 billion instead of 20 million, which is a much bigger difference
it seems likely that digital technology will be crucial in enabling there to be far more humans off earth than on earth; o'neill cylinders could enable many orders of magnitude more physical humans even within this solar system
to say nothing of the possibility of backing up your mind with a brain scan and thus becoming immortal, and possibly forking into more copies of your mind than there are humans alive today
it seems likely that digital technology will be crucial in enabling there to be far more humans off earth than on earth; o'neill cylinders could enable many orders of magnitude more physical humans even within this solar system
to say nothing of the possibility of backing up your mind with a brain scan and thus becoming immortal, and possibly forking into more copies of your mind than there are humans alive today
(nitpick, transistors aren't digital)