The only response I ever get is "But the base will grow and margin orders will level off the volatility." Those arguments don't address my concern that a currency needs to have some psychological element built in like fiat does.
Your concerns provably don't matter.
By every objective measurement, adoption is proceeding exponentially despite every so-called problem. Bitcoin is already a successful technology because people are choosing to use it. Actions speak louder than words, and the actions of the market tell us that whatever issues Bitcoin may have none of them are deal breakers. Some of the flaws that various concern trolls want to "fix" are actually selling points.
If you're going to start out an argument with the premise that Bitcoin is fatally flawed then you're as grounded in the real world as someone who starts an paper on hydrology by assuming that water flows uphill. If you want to be taken seriously you've got to acknowledge reality first, then try to make the case that the gains could be even greater in some alternate scenario.
I did offer a solution. In fact, my concerns are slowly and indirectly being addressed. Besides, I didn't claim Bitcoin is "fatally flawed." I claimed the current version doesn't address the needs of a currency very well. So far, most of the development has focused on the payment protocol and virtual commodity exchanges. Only now are currency issues being addressed in things like "colored coin" and "master coin," both indicative of usefulness as currencies, hence the terms 'coins.' They will play a large part in addressing the psychological factors needed to be acceptable as more than a commodity as a full-fledged currency.
Listen to the critics of Bitcoin sometime and don't be so dismissive when they say it's not "backed" by anything. Surely they are not experts on the subject, but their sentiment is worth noting. Currencies are indeed "backed" by their history and infrastructure used to establish their value. They also have their "network effect" so often claimed by Bitcoinia. Their currencies are not just backed by faith, but also by established rules such as "legal tender" and taxes that limit wealth aggregation. Bitcoin does have a clear advantage, and that is math. Bitcoin also has a lot of catching up to do in all areas of finance that have been claimed by countless other financial instruments besides currency, such as ownership and economic controls. Again, these will be easily addressed mathematically, transparently, and fairly.