Maybe not as much of a problem as a disappointment. I'm a collector first, and not ashamed to admit that. As a collector, I'd like to hope that my portfolio of personal sets continues to consistently grow in value.
Honestly, I probably won't sell even half of what I've purchased because I value those sets like I do my art, sports Memorabilia and historical treasures. It is nice to know that I could sell them at some point if I wanted or needed to and come out ahead. If over hoarding / market saturation lead to a situation where exclusive sets don't appreciate strongly anymore, I'd probably have to reevaluate the sizeable chunk of change I throw down each month on my personal collection.
As a reseller, I can probably adapt and overcome and continue to make a profit. My best gains so far haven't been from large or exclusive sets. I'm just not sure that I have the extra time to devote to doing it well, and doing it half-a** is a recipe for disaster.