Warpath pure phys crit/crit multi

Need some help on a pure physical damage warpath build. I’m at a loss seeing other builds doing 700k+ crits in videos meanwhile the biggest hit ive seen is 4k.

My stats:
Increased Physical Damage: 747%
Increased Melee Damage: 145%
Armor Shred: 120%
Melee Critical Strike Chance (while channeling Warpath): 98%
Critical Strike Multiplier: 302%
Warpath Level: 23
Weapon: 2h Zweihander with T7 +100 Melee Physical, T5 188% Increased Physical Damage

DPS showing while channeling Warpath: 50374

Why is the damage so bad?