8,000,000 / 8,000,000,000 = 0.1%.
This means that Satan can mislead 99.9% (100 - 0.1) of the people in the world.
After 1,000 years, when humankind will be perfect again, since "The number of these is as the sand of the sea" (Revelation 20:8), once again a huge amount of perfect people will get misled by Satan.
If the reason for this big number was because of the imperfection, that means Adam and Eve's fault, not so many "perfect" people should get misled by Satan in the future paradise.
So, could you think that 99.9% of the perfect angels are demons misled by Satan? If not, why is Satan able or allowed to mislead so many more (imperfect and) perfect humans than angels?
Another question is: if God "does not desire anyone to be destroyed" (2 Peter 3:9), why does He allow Satan to be able to mislead 99.9% of people since He knows in advance that "many, I tell you, will seek to get in but will not be able" (Luke 13:24), and "The number of these is as the sand of the sea" (Revelation 20:8), and "Go in through the narrow gate, because broad is the gate and spacious is the road leading off into destruction, and many are going in through it; whereas narrow is the gate and cramped the road leading off into life, and few are finding it" (Matthew 7:13, 14)? Should not it be the other way around as a logical statistic?