If you ever talk about cryptocurrency with reletives you probably hear these questions a lot, and if you didn't prepare you may not have known a good answer, so here's the best answers I think you can give for these questions
Q: What backs Crytocurrency?
A: what backs Cryptocurrency can change, but some most commonly it is the technology that backs the currency. Example, Ethereum is backed by it's smart contract technology.(Bonus response) What backs the US Dollar since the gold standard was taken away.
Q: What if you lose Wifi or Electricity, than your Bitcoin is worthless right?
A: If the grid just went down then I think money for you and me will be the least of our problems. I think it will be the rioters who will be the real problem there.
Q: If the price of Cryptocurrencies fluxuates so much, how can you protect your investments?
A: There's no safe investments, period. The best thing you can do is invest in something that you don't think will fluxuate as much, which there are plenty of cryptocurrencies that don't.
Q: Cryptocurrency is just a Ponzi scheme since you can't buy anything with it right?
A: actually plenty of places already accept Bitcoin in it's own and if you really want, there are cards you can get where you go to the store with your Bitcoin card and buy anything that cost US dollars, in Bitcoin.
Q: can't you lose all your bitcoin if you get hacked?
A: No, not if you're smart and you store protect your funds by keeping them in some form of hardware or paper wallet. Example, Leger Nano S, Trezor. You are in control of your own money, can you say the same about your money in the bank?
Q: What if you want to turn your cryptocurrencies back into "real money"?
A: There are plenty of services to do so but honestly I see no reason at the moment while I'm still making money.