[balnaphone]

Practically speaking, unverifiable and unfalsifiable.

They say once in 7.5 million years, so why don’t they show the previous 7.5 million years?

If that's not possible, and we only have 1989-2023 data, then the 7.5 million year comment is particularly ridiculous, as is making any generalization with data for only 0.0001% of the time span in question.

[BobbyJo]

The timespan is just a more easily digested framing of the odds. It's meant to be easier for a layman to understand, and doesn't actually have anything to do with what things would look like over 7.5 million years. That would take models with an impossible level of detail about planet scale dynamics.