How is it fair that kali yuga is the only bad yuga because Dwapara Yuga, Treta Yuga, and Satya yuga have most dharma while Kali yuga has the least dharma
Who said Kali Yug is bad ?
Ved Vyasa himself said "Kali Sadhu:" - meaning Kali is great
Each Yug has its own methods of attaining Bhagavan. Kali is the easiest.
dhyayan krite yajan yajnais
tretayam dvapare arcayan
yad apnoti tad apnoti
kalau sankirtya kesavam
Whatever is achieved by dhyana in Satya-yuga,
by the performance of yagna in Treta-yuga,
and by puja in Dvapara-yuga,
that is obtained in Kali-yuga by glorifying Keshava.
So, in Kali, we don't have to do arduous penances because Bhagavan is very lenient - he knows that most people born in this Yug are spiritually weak and degraded and sinful, so he gave them an easy rope to climb out.