The disease of the heart (love of worldly things)

ذَٰلِكَ بِأَنَّهُمُ ٱسْتَحَبُّوا۟ ٱلْحَيَوٰةَ ٱلدُّنْيَا عَلَى ٱلْـَٔاخِرَةِ وَأَنَّ ٱللَّهَ لَا يَهْدِى ٱلْقَوْمَ ٱلْكَـٰفِرِينَ

That is because they preferred the worldly life over the Hereafter and that Allāh does not guide the disbelieving people.