If a believer were to know the punishment (in Hell) none would have the audacity to aspire for Paradise (but he would earnestly desire to be rescued from Hell), and if a non-believer were to know what is there with Allah as a mercy. none would have been disappointed in regard to Paradise.

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لَوْ يَعْلَمُ الْمُؤْمِنُ مَا عِنْدَ اللَّهِ مِنَ الْعُقُوبَةِ مَا طَمِعَ بِجَنَّتِهِ أَحَدٌ وَلَوْ يَعْلَمُ الْكَافِرُ مَا عِنْدَ اللَّهِ مِنَ الرَّحْمَةِ مَا قَنِطَ مِنْ جَنَّتِهِ أَحَدٌ