Whether they go up or down relative to USD is irrelevant, ups and downs relative to bitcoin are more useful since as long as your trading results in increasing numbers of bitcoins you are getting ahead and will be way ahead the next time USD crashes abysmally relative to bitcoin, which is quite a common occurrence. For example late last year USD crashed to something like 1/10th of its value or worse compared to bitcoin, and in the few years before that it crashed to what, 1/1000th of its relative value or worse?
Comparing to something like USD which is always in general tending downward and might even be in its death-throes seems silly compared to checking against something like bitcoin that keeps on tending upward despite the best efforts of various parties and opponents and such to drive it down.
-MarkM-
The dollar crashed to 1/10th its value?
Look I have no faith in QE and the future of the dollar as the reserve currency either but if it lost 1/10th of its value last year we'd be in the second Great Depression right now.