This book is still in print, why are you sharing a pdf copy?

Corrected, thanks, though a 1954 copy, but a lot of copies online. A good one, nevertheless (i.e., something you might actually pay for a paper copy).

Why not? Darrell Huff died in 2001, and under any respectable copyright system his work would have ended up in the public domain in 1979, or at least with his death.