You are already searching an impossible to find needle in a haystack so why are you making your own job harder by doing the search using the HD key derivation function? Why not just search for private keys and avoid all the extra overhead of the key derivation?!
If you were able to find a private key to steal other people's money (which you would never be able to) it doesn't matter if that key was derived from a master key or was found at random.

It is like wanting to find z from x+y=z but instead of first adding x and y you go ahead and compute pow, sqr, sqrt, cos, sin, sin^-1,... of both x and y then finally add x and y to find z.