ICN-BKK has 8 carriers because there is a lot of demand. There is only so much demand that can be stimulated with low fares. For those wanting to travel somewhere for tourism because it's on their bucket list, or they have families there, lower fare encourage them to visit for the first time, and for those that have been already, visit more often. I can't imagine there are many Koreans eager to travel to Lahore no matter how cheap the airfare is. Geneva is an expensive city that don't mix well with low fare travelers.
The problem is that competing only on low fares on an already VERY crowded route invites a race to the bottom. I doubt Air Premia's pockets are as deep as those of larger carriers which could match Air Premia's discounts on ICN-BKK as a defensive tactic in order to prevent erosion of their market share.
If Premia is offering cheap fares to attract customers, these could also be easily matched by low-cost rivals like Thai Air Asia, Jin Air, Air Busan and Eastar Jet, all of which have an interest in fending off an upstart on what you note is a popular route.