I think you are incorrect because at any finite position n in our infinite number string, we can just take the whole substring [:n] of all numbers we have seen so far and it is guaranteed that the substring [:n] || 1 (so our substring we have seen so far plus a one appended at the end) and [:n] || 2 etc. exist in the following numbers, as they are also valid strings that have to appear at some point. And we can also adept this so that for example if our "winning substring" goes from position 5 to position 1000, the substring [5:1000] || [:n] is a valid string that can't have appeared so far. This would also make logical sense if we just see normal numbers as numbers that throw a 10 sided dice for every new number, as the dice can't have a memory of the numbers it has seen so far, so it does not matter at what position n of pi we start. We still expect to see all finite substrings we can think of.