Bitcoin and Block Chain Technology is extensively discussed here on Medium. I am sure I have read more than a dozen stories on Medium on these subjects.
There is a transaction latency and transaction fees. You are right no special fee for international transfers.
Bitcoin has not always gone up. I am sure you already knew that.
Are you familiar with the Story of Mt. Gox Hack?
https://www.wired.com/2014/03/bitcoin-exchange
If they can be hacked anyone could be hacked but they did cover their clients losses.
Your wallet is only as secure as your password.
Setting up a Bitcoin wallet and filling it with Bitcoins is way more complicated than any other financial transaction I have done except my first mortgage or getting a balance transfer to closeout an account from a reluctant financial institution. Just learning what it would take to set up a Bitcoin wallet was a lot of effort.
Some day cryptocurrency will be user friendly but then it will probably no longer appreciating as rapidly.
I am glad you are active here on Medium.
TEK
