Bitcoin ?

Bitcoin is a virtual currency, virtual means that it has no physical form like other currency, it is a digital currency. ... it takes about two to three percent transaction fee to pay with a common debit / credit card, but bitcoin has nothing like this .In this currency, you can also earn money very quickly and very soon money can drown you. 

1. When everyone buys it, its rate becomes high. But when people start selling it, its rate is down. 

2.But yes, there is no guarantee of currency in it. If you get drowned in the process, there is no confirmation that you will get it back or not.

3.But this does not happen because it has more than two crore users. All over the world people who trade in bitcoin.