In Bible times, conventioners had to make sacrifices to attend. So do many today.
مَثَلًا ،‏ كَانَ عَلَى ٱلَّذِينَ حَضَرُوا ٱلْمَحَافِلَ فِي أَزْمِنَةِ ٱلْكِتَابِ ٱلْمُقَدَّسِ ٱلْقِيَامُ بِتَضْحِيَاتٍ كَبِيرَةٍ .‏