I just noticed this post now. It's been five years, but it's still relevant.
2) Inflation gives people an incentive to spend money. Nonsense. Inflation means you can get a higher interest rate if you save the money, giving you an equal incentive to save.
Inflation gives you an incentive to invest the money rather than just stuffing it under the mattress, either directly, by sticking it in a savings account where it's used to make loans, or by buying something that will give you future benefits.
Right, but that doesn't matter. I agree that inflation changes the way you invest money, but it doesn't change your incentive to spend versus invest. (Stuffing money in your mattress acts just like a general investment in the economy because taking money out of circulation increases other people's buying power.)
3) Deflation gives you an incentive to hold money. Nonsense. You can just as easily sell the right to hold that money and get its value today rather than holding it yourself.
Why should someone buy it for more than it'd cost them to get the same amount of money right now, though?
What difference does it make how much they buy it for? Say Bitcoin weren't deflationary and so didn't include the right to hold it and make money, and say the price of bitcoin were $300. Now, say you keep everything else the same but make Bitcoin deflationary so it now includes the right to hold it through its appreciation. The net present value of a bitcoin might now be, say, $100 because it includes the appreciation right. So nobody's willing to sell a bitcoin for less than $400.
There's still not a special incentive to hold it. You can either hold it, and get the value of its appreciation, or sell it for $400 today, which includes that extra $100 that is the value of its appreciation. Either way, you get the same value.
It is essentially impossible to have predictable, excessive, prolonged deflation. Why? Because if we all agreed that some commodity would be worth $500 in a month, almost nobody would sell it for $450 today.
The price of a bitcoin today includes the expected value of its future appreciation moderated by the risk that this appreciation may not materialize. If that appreciation were certain, it would have already happened.