I don't get it and some people have tried explaining but it seems to ultimately boil down to "I just don't like/want to" which to me is incredibly insufficient. These people would rather throw away perfect food even when they made it themselves. Leaving out certain exceptions that don't keep well, many dishes can even taste better as leftovers while others can be combined to form entirely new dishes.
Edit: to those asking, this is about several people in my life who throw out a lot of food because they don't leftovers and when I've asked them about it I've felt that they don't really give good answers. These are people who afaik don't have eating disorders since they eat normally but will not do takeaway at restaurants or save extra portions of a meal they've cooked.
I eat 90% of my leftovers but every now and then I simply make too much. I live alone and tend to cook full recipes. Normally I just have that for the next few days, but sometimes I get bored and make something else. I tell myself I'll just eat the leftovers the next day but sometimes they get less and less appealing and I end up waiting too long.
I think this happens to everyone from time to time. I've had to throw away vegetables because I simply forgot about them. The situation I'm asking about is more egregious in that any leftovers at all are never eaten because they are leftovers.
Yeah that's mind-blowing to me. Taking perfectly good food and just throwing it out because it wasn't eaten right away... Even if it doesn't matter to somebody financially, why waste it?