Question About Predicting Chaotic Era

I have a question about the San Ti’s motivations and the nature of the three body problem. I understand that the issue is that no matter their advancement eventually the San Ti won’t be able to predict when a chaotic era will occur far enough out in the future. My question is, if they have means to protect themselves during a chaotic era, why does it matter if they can’t predict it out indefinitely?

Is the issue that they don’t have means of saving themselves like they do in the simulation? Is the issue that they are just tired of having to start a lot of their society over?

This could be a silly question but I don’t understand the problem with being unable to predict a chaotic era indefinitely out into the future if it can be predicted in the short term?