Yes. 4 to 8 billion is a 2X jump.
You made an important point, with all things considered, arguably the quality of life globally is probably better today during and after the 2X jump. So mankind have after to sustain it.
Trouble is population jump is in GP.
So all else being equal next time you will look at this corner of this apartment world population will be 16 Billion! Now just thinking about it I am getting very nervous. Statistically my math says there is a nonzero possibility that you and I won’t be here if/when that happens! And yet that day could be out there.
Most scientists agree that we don’t have resources to get there, so population growth will have to slow down long before that.
The current world population of 7.6 billion is expected to reach 8.6 billion in 2030, 9.8 billion in 2050 and 11.2 billion in 2100, according to a new United nations study
I have no way of predicting if this projection will be true or not. But that 10 billion number by 2050 makes me very nervous.