Bank could satisfy the human's nature of seeking safety and saving, and at business level they provide the most important driven power of economy -- loan
Since BTC is not good at issueing loans, it will not replace banks in any foreseeable future, it must find a better usage to be more attractive, currently the biggest benefit I think is to transfer money internationally without passing through bank/forex (save at least 3%), but that function is still limited, and those who need this functionality typically have millions of dollar to transfer, that will shake the exchange rate greatly
I disagree. Bitcoin loans lack the power of government enforcement because lenders and lendees are often in different jurisdictions where collections aren't worth the cost, though I'm sure I'm not the only one who's taken a Promissory Note. That's really the only disadvantage BTC lending currently suffers (we don't "know" them, nor can we contact them in meat-space). That said, US payday loans typically make 9% profit off short-term loans. 4-15% is a pretty typical MPR with BTC. In the UK, 30% of loans are defaulted on (that is, not repaid after 30 days of the agreed repay date), and 10% of those are written off (no repayment 90 days after repay date). That's almost perfectly in line with the data we have for BTC loans (though much fewer than 30% default -- typically, if not repaid within a few days after the repay date, it's going to eventually be written off - it's roughly 10% default rate both for 30D & 90D).
For lendees, rates are often lower than other short-term loan options, it can take less than an hour to go from applying to receiving coins, it's done online, and in most cases - there is no extensive background or credit check. Bitcoin lending operates largely independent of fiat lending, allowing lendees who previously made bad decisions to redeem and benefit themselves. Loan terms are often extremely flexible, with lower rates for those who can make partial payments per week, which fits miners, who're effectively taking out payday loans, and for which specific loan calculators actually exist (plug in MH/s, get rate, expected payment/week, max loan amount).
