My Amazon bestseller made me nothing
I think the biggest problem here is the word 'bestseller'. 4000 is not a number I would associate with that word, prior to knowing what algorithms are used to determine those lists.My guess is that 'bestseller' lists are far more a marketing tool than any reflection of how books are selling.I've published technical books that sold in that rough ballpark, and I can tell you they never came near any bestseller list (nor should they have).