to fret or worry about the troubles or fates of historical figures or people from the past

他读史书入戏太深，不时为书中的悲剧替古人耽忧。

to worry unnecessarily about matters that are already settled, unchangeable, or do not concern oneself; to cry over spilt milk

既然事情已经过去很久了，你就没必要再替古人耽忧了。