I think the current status of coin generation difficulty and the arms race of private-source GPU coin generation has discouraged some people's interest in the coin generation game/lottery which - rightly or wrongly - has been the motivation for a lot of people's involvement. It also seems to be a symptom of a meta-flaw in the project design, because open source projects want to ENCOURAGE the contribution and sharing of code, but the nature of the coin generation process seems to inherently reward and incentivize closed-source forks. Another set of concerns is the possibility of non-conforming clients exploiting the system (as seems to have occurred somewhat recently causing the 0.3.9 update) and the resiliency of the network to malicious behavior, and the potential fragility of your bitcoin bank account if you mess up handling your wallet file. Last but not least is the meta-issue of understanding how to deal with your local laws and regulations concerning taxes and money.

I love the idea of bitcoin, but I have donated all my bitcoins to the EFF donation thread now and am no longer actively participating in the bitcoin economy because of how the above issues apply to me. This is not intended as criticism of bitcoin, just as a user reporting why they are no longer using the software currently.

1. I'm not interested in running multiple computers at max cpu usage for weeks to try to generate a rather trivial value of coins, especially when I know GPU users have vastly higher efficiency
2. The mechanics of keeping my wallet files private and constantly backed up with a fresh copy gives me "data stress"
3. All software has bugs. Software that is related to money is an inevitable target of attacks, and there is no FDIC backing or legal system remedy available in the case of problems
4. I don't really know how to document and declare transactions in bitcoins for legal and tax purposes and I'm scared of getting it wrong

In other words, I see costs/risks to using bitcoin and trying to participate in the bitcoin economy without seeing practical benefits other than how much I like the idea of bitcoin and think its cool software. I want bitcoin to succeed, but my current evaluation of my economic self-interest is that I have no reason to run the client and no reason to purchase bitcoins. I also do not feel motivated to "promote" bitcoin because that makes me feel like I am basically working to advocate the economic interests of those who already hold large quantities of bitcoin wealth. The have/have-not dichotomy is another structural issue: "come join our economy! you can be a peasant!" is a hard marketing sell.