It is advised to fear the Day of judgement because nothing would be more terrifying than that Hour! Everyone would forget the worldly affairs and they would appear intoxicated because of the intensity of the hour.
“O mankind, fear your Lord. Indeed, the convulsion of the [final] Hour is a terrible thing.” Quran (Surah Hajj, 1)
“On the Day you see it every nursing mother will be distracted from that [child] she was nursing, and every pregnant woman will abort her pregnancy, and you will see the people [appearing] intoxicated while they are not intoxicated; but the punishment of Allah is severe.” Quran (Surah Hajj, 2)