UUIDs have 2
128 possible identifiers. They are also designed to be collision-proof. Wikipedia
says:
To put these numbers into perspective, one's annual risk of being hit by a meteorite is estimated to be one chance in 17 billion, that means the probability is about 0.00000000006 (6 × 10−11), equivalent to the odds of creating a few tens of trillions of UUIDs in a year and having one duplicate. In other words, only after generating 1 billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. The probability of one duplicate would be about 50% if every person on earth owns 600 million UUIDs.
Compare this to Bitcoin's 2
160 possible addresses. Bitcoin has:
1461501637330902918203684832716283019655932542976 addresses
UUIDs have:
340282366920938463463374607431768211456 identifiers
Is it possible the probabilities are misunderstood, similar in some way to the Birthday problem? (Where the odds of 2 people in a room having the same birthday are very much reduced from what one would expect)
I took that into account in my "ten addresses per second" example.