Yep. HP just isn't something to care about as you go higher floors since it costs more to survive a hit and still have HP and damage Reduction , so much so that you'll lose DMG.
Good solution ofc is Block/dodge or both since it just blocks or dodges attacks and a high chance can get you a pretty decent survival. Other factors include Sanctuary mythic to revive , CCs to stun, blind , freeze enemies , movement speed to quickly move about, teleportation, etc.
Also distance as is with the case of Flintlocks and other skills that are rapid fire.
For that chakram build with whirling blades , use Periphery rather than actual whirling blades skill with chakram , attack speed for faster chakram returns and increase DMG of it.
Chakram DMG can be increased by 4+ Extra Attack, 4+ Multi Attack, Skilled , Blindside , Living Force , Timewarp and many more things. Being able to damage enemies fast enough also can be an element of survival.