Why do people often think that the past was better than the present or future?

I think people often think the past was better than the present or the future, because humans are generally scared of the unknown and only see the positive aspect of things in the past. People since the beginning of time have been scared of the new and unknown. That tendency still lives on today, and is the reason why some individuals fear the future. Human memory has a tendency to only remember the best experiences from the past such as a happy childhood, and forgetting about the more unfortunate ones. In conclusion people think that the past was better han the present or the future because their memory fails to remember the negative memories from the past, and they are scared of what's about to come.