>Investment won't ever stop, it just behaves more like a there is a minimum interest rate. No matter what the deflation is, I can still loan out $100 and expect $110 back within a year and make a bigger profit than holding on to it.

But is that $10 profit going to be worth the risk of default when an investor could get a satisfactory return by just sitting on the money in the first place? What incentive does an investor have to take bets and possibly lose thousands or millions of dollars when his money appreciates considerably without doing anything?

To use a case from the bitcoin economy, we all know the story of the pizza that someone bought when the x-rate was something like 3 cents per coin. Today, the 10k btc spent on that pizza would have been worth $100k! This story is often told to try to incent people to get into btc, with the implication that "if you forgo the cost of one pizza, in a little while that will be worth thousands of dollars", without realizing that this exactly is the problem with a btc-based economy; if everyone is forgoing their metaphorical pizza in the hope of exponential growth in currency value, the market will be unusable.