Here is a good parable.
Possibility increases drastically when there is divine intervention.
lolGiven your example of 1 billion users at 10 addresses each:
There are 2^160 or about 1,460,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 possible addresses
In your scenario, 1,000,000,000 people are using 10 addresses each for a total of 10,000,000,000 possible addresses
10,000,000,000 / 2^160 should yield the probability of a collision occurring
10,000,000,000 / 2^160 = 0.00000000000000000000000000000000000000684
So the chances of a collision occurring in your scenario are approximately 0.000000000000000000000000000000000000684%
There are 2^160 or about 1,460,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 possible addresses
In your scenario, 1,000,000,000 people are using 10 addresses each for a total of 10,000,000,000 possible addresses
10,000,000,000 / 2^160 should yield the probability of a collision occurring
10,000,000,000 / 2^160 = 0.00000000000000000000000000000000000000684
So the chances of a collision occurring in your scenario are approximately 0.000000000000000000000000000000000000684%
Possibility increases drastically when there is divine intervention.
I like your answer. 😂