DNA: Why is bad habit of wasting food not ending?

Two days from now, on 29th September, the whole world will celebrate International Day of Awareness of Food Loss and Waste. On this day, people will be made aware to stop the wastage of food and drink and this awareness campaign has been going for the past 3 years. But alas, people have a bad habit of leaving food on their plate and this habit is not ending anytime soon.