The main issue that I see with this is that ability to buy something does not mean everyone has an equal ability to manage inventory, market items, sell items, and process orders. The buying part is really the easy part in all of this. In no way is this a level playing field, and it never will be because of incompetence, laziness, differing skill levels, etc...
This is not a slam on anyone specifically, but I would say that based on the listings we see and based on many of the things posted here in the forums and some of the blog articles that a large percentage of would-be investors are somewhat incompetent when it comes to effectively doing all of the activities required to operate profitably in a secondary market. This could be because they just haven't learned how to do it yet, or it could be that they just don't care.
As you mentioned quick-flipping, it often gets a bad rap here because people say the time involved isn't worth the return. This is at best short-sighted. While I have no definitive proof, this is evidence to me that the people attempting it haven't really thought through what they're doing. Whenever you have a process that is inconsistent or inefficient, results will be impacted. The only reason I can quick-flip things profitably is because we're following a very well-defined, predictable process that produces predictable results. For example, I don't print shipping labels the way many of you do, I use standard box sizes, I buy boxes in bulk at really low prices, I use automation to manage inventory and create listings, etc... People also have issues with how long it takes to list things, which is yet another indication that people are using ineffective or no automation techniques to speed all of this up. This results in low-quality listings that take people a ton of time to create.
Just wait until close to Christmas when we see people whining about hitting item and selling limits on eBay that they don't know exist, or all of the complaints we will see about negative feedback because they didn't take the time to properly package and ship things. You'll see some people drop out of the market after that.