Why is it that people don't know what they got until it's gone?

Question

Seems to be a common theme.

Answer 1

Because we take the everyday things that are done for us for granted. We may know the process but we don't understand and or we are not grateful for the efforts put in until it can't or won't be done anymore.
For instance the rain sometimes we are upset because it may have hindered us from doing a particular task and we blast it when it doesn't fall or even worse a drought we are short on most things(water. food etc)which we need and is vital to our everyday activities.

It is as simple as that.

Answer 2

Spend to much time wanting more rather than appreciating.