Is not about Dex/DMG

do the math here,

DPS Caculator =

[(Weapon DMG) + (All DMG Bonus from EQ) + (Skill Dmg Bonus)] x [Weapon Atk Speed-1 + [(1x Bonus ATK Speed)-1] + (Total Dex/100)]

Since you can get massive Dmg from weapon only, so focus only DMG in weapon. Simple Example :

(without counting any other bonus)
If you got 1000dex, with Weapon DPS 100, roughly = 1000DPS
but if you switch to weapon with DPS120, outcome = 1200DPS