if you buy a bitcoin today, you can trust that it is real, trade-able and worth today's market price on the exchange. you can even use it to buy physical goods at the market price without question.
yes, the day-to-day value is unstable due to inherent factors but that is offset by other benefits.
there are various levels of trust for various financial instruments for different purposes. just like with tools, there is no one perfect instrument that does everything
IMO, the only way we will see the end of bitcoin is grid collapse, cheap quantum computing or government attack
I can take a dollar and place it in my wallet, its real. Bitcoins have no physical form in the real world. And printouts don't count.
And its only trade-able IF someone else agrees that it is. I can't go to my local Krogers and use bitcoins nor the local gas station.
Bottom line Bitcoins are vapor Mt. Gox proved such. And their plummeting value shows they are nothing but a bad investment.