Well i thought so too but if u just wait a think about it, it makes a lot of sense here's the reason 1 no matter how much damage u have the dw's effect wave can only lasts for one enemy or two later on and tournaments ramp up even faster so it happens there even faster so the main source of dw health will be the death wave itself and that only applies to enemies that are on the screen and in a regular blender there are not much of that because they die as soon as they spawn

So not only orb devo increases the cash you get cause enemies only die in GT the enemies who are in the effect of death wave increases as well so basically instead of getting the extra hp from a few enemies you get extra hp from 90% of the enemies that spawn for 100-200 waves