I can't think Bitcoin will destroy. How is it possible?  Bitcoin is mother coin. It's not like other alt coin. It's not controlled by any organization. Bitcoin is very strong. It's value is different from other alt coin. Everywhere using now Bitcoin specially in online. So I think it's not possible to become destroy.

cash and bitcoin has different usage, if the bitcoin is better than method of payment cash or online shopping center in chas. but cash or any payment methods also have the risk of counterfeit money and actions such as theft then that's just better bitcoin instead of cash, bitcoin easily saved the price value is higher than the cash

I first learned about the coin in a website can't remember much of it but just ignored the coin that time.

What does airdrop means? is it the same as ICO?