But I think you need to have a general affection for design in general to really get anything out of the book.
In my experience you don't :-) At least, I've seen it switch many people out of the design == "making things pretty" mindset into something more productive. It's always on my reading list for people who don't get design, or people who understand that they need to get design. Seems be effective with both groups.
I think it has something to do with it not being written as a "design" book per se. Remember the original 1988 title was "The Psychology of Everyday Things". It's up there with "Peopleware" as a book I keep buying for clients :-)
But I think the question is whether you can be a successful entrepreneur without having some sense or idea about design.
In my experience from working with many many startups the entrepreneurs either get it or they don't. In fact if they don't they wont even entertain the idea that they don't get it.
Most skillful people will tend to develop good taste and a sense of design in and around their own field of expertise. The Design of Everyday Things has helped people I know expand that sense beyond its original narrower confines to, as the title suggests, the world of everyday things.
The downside is that now some of them think they can instantly render a well-founded opinion on anything relating to design. Although that may simply be a corollary of the general phenomenon where experts in one field (and programmers and engineers may be the worst) think they possess the master key to critical thinking and problem solving in any and all fields.
I guess the book might make you appreciate design and that might affect your sensitivity to design.
But I think you need to have a general affection for design in general to really get anything out of the book.
Otherwise you run the risk of thinking your understand design now that you have read a book about it.
Just my opinion of course.