because i did. i want to say that there's a larger purpose behind doing this, like the relentless pursuit of perfection or whatever, but it's really just one of those things i did because it was there. also i got an exclusive title, something like 3700 star gems and enough precision will 2 capsules to corner the ship 4 market. but that's just a bonus.
for further context: pso2 really does task you with fighting omega masquerader across 999 floors. also the last floor features a special variant that does lethal damage with every hit; there are ways to mitigate this which i use, but it's still important to know the fight very well to do this.