If it is to believe that this man had got dealing on some other digital currencies like the ETH, USDT and Gold as you said as a matter of him trading on them, then I don't see most of this his questions necessary because he should be familiar with some even though he does not have deep knowledge of them but I would reserve it to say that you might be on his trial to see how good you could make him understand better as he maybe interested about it.

But in a simple response is that...
Bitcoin is a reputable digital currency as a matter of fact, first ever developed cryptocurrency with a high rate of volatility which can be utilized for alternative source of making payments with the potential to holding hedge of values.

Bitcoin values depends on the ratios of demands and supplies of it.

Bitcoin is a global legal financial technology but some government places are against it due to the fact that it is a decentralized currency which can not be controlled by the authorities. So, it legalities depends on each and every governance in a society to decide it's policies and also central regulations through the central exchanges.

Bitcoin can always be stolen if owners are careless with their security systems and loose of holding privately.

Bitcoin Debit cards are only issued to places where is installed Bitcoin ATM which are most especially places where Bitcoin is generally accepted for legal tenders probably for means of payments in some institutions and large companies. It gives varieties of flexible executions of transactions.

Bitcoin has come to stay as no particular entity could decide what happens to Bitcoin entirely so, it can not be shutdown but can be hacked when users steps of the toes of online based scammers.

First Bitcoin is not an exchange but a asset currency of it own but can decide if you want to trade/exchange it to fiats or other cryptocurrencies and can also be served as an exchange for payments of goods and services.