I think you are not up to date on fractional reserve banking. The multiplication of money comes about when the money is redeposited in another account, either by the lender or the person he buys stuff from. The money supply thus extended, is somewhat subjective, as it depends on the psyche of the persons involved, do they really have these money fully, or is it only partial money.
Wrong.
They don't have real money, they still have credits.
It is not money until you cash it out of the bank and hold the banknotes, and they can't multiplicate that, as I already explained.
You can do the exact same thing with bitcoins, it's really no different: you can't print money, you can't print bitcoins.
The problem: if bitcoin becomes popular in a growing economy there is no incentive to lend bitcoins to anyone else. Why? Because the would be lender can just sit on his or her bitcoin stash and wait for the bitcoins to progressively become worth more without any effort. A growing economy means more goods chasing a dwindling supply of bitcoins (some are lost to HDD crashes, etc). In this scenario why risk lending out and losing your bitcoins?
Anyone borrowing bitcoins would have to put in an extraordinary amount of effort to repay the loan, as bitcoins in a growing economy are worth more as time goes by. To borrow a bitcoin today for business purposes and repay it in a year's time means having to do a lot of work to repay that bitcoin even before any interest is considered.
Bitcoin cannot be the basis of a modern economy as we know it. The incentive to sit on a pile of bitcoins and wait for their purchasing power to improve is too great.
This is skewed, try to focus with more attention to
every detail.
1. bitcoins will likely appreciate in value, but if you lend them, you'll have greater gains, hence lending makes sense
2. paying them back appears to be more difficult, but again this is not fully true: if you borrow bitcoins I can expect you to need
bitcoins and
gain bitcoins doinh your business (otherwise you are stupid and should have borrowed something else) --> you owe bitcoins, you earn bitcoins, you pay back; the exchange rate with other currencies is irrelevant (if it is, you botched your business plan and you didn't really need to borrow
bitcoins)