But the random part of a UUIDv7 is 74 bits... larger than a 64-bit integer of random values. Larger than many systems use in total when generating random keys

But the random part of a UUIDv7 is 74 bits... larger than a 64-bit integer of random values. Larger than many systems use in total when generating random keys for such things. Likely a larger number of values than the total number of comments here on HN over a couple decades. It's emphatically NOT guessable.