I found a fallacy. Let's crack it, Allen's.

Assuming that time is infinite, the greater the chance of flying back by time machine in the future. Similarly, for people in the future, the greater the range of choosing which time to fly to. Assuming that it is random, the probability of choosing to fly to the present is smaller.

It's up to you to take a piece of paper and write a sentence to N's descendants: When you see this paper, please fly back to XX to meet your ancestors. If you don't have a time machine, please pass it on to your descendants. Then seal it up and keep it properly. If all goes well, it is estimated that you will meet your future grandson in a few minutes. Good luck with your experiment. Amen. . . .