The Bible does not specifically say what aspect of the world Demas loved, causing him to abandon Paul.
أَوْ رُبَّمَا يُحَاوِلُ أَنْ يَحْمِلَنَا عَلَى مَحَبَّةِ ٱلْعَالَمِ وَإِهْمَالِ عِبَادَتِنَا لِيَهْوَهَ .‏ —‏ اقرأ ١ يوحنا ٢ :‏ ​ ١٥ ،‏ ١٦‏ .‏