I agree that your contribution to the government is small, although it's not zero. I assume North Korea wouldn't be allowing Western tourists to come on these trips otherwise; they clearly see an advantage to your visit (unless they are just deluded that Western tourists will be fooled by the propaganda).

But, what are the chances that your time there will really shed any more light on North Korea? Encouraging friends to read "Nothing to Envy: Ordinary Lives in North Korea", for example, or simply reading it or another similar book yourself and sharing your thoughts would arguably shed more light than a brief government managed trip and a blog post.

Edit: I'd love to hear why you disagree rather than just downvoting. I've wondered about making this trip myself in the past and this is where I've settled, but would be happy to hear further arguments.