bitcoin cannot replace currency in the world because price is not stable.
correct. bitcoin is not going to
replace anything. it will be used as a currency for those who want a better privacy and a benefit of using a decentralized currency instead of the banks and their centralization and all the privacy hazards that come from it.
currency should be more stable.
"should" is the wrong word. a currency is better to be more stable but if it wasn't, nothing is going to change about it.
USD currency price is up and down 1-2% in 1 month.
and how long has USD been around? and how many people are using it?
when bitcoin became as old and as popular as USD its price will also become stable. much more stable.
what will people think if they just change USD to bitcoin then their money down 10% in 10 minutes?
yes they will and they are doing it as we speak.
bitcoin can become stock but cannot become currency
bitcoin IS a currency and it IS being used as a currency and it also IS an investment whether you people accept it or not. the world don't care about your or my opinion the word is using bitcoin as a currency too.