It is obvious that people whom say bitcoin has no value has no idea about the technology and how their own money is held.
You can hold cash if the power goes down. But it is obvious, governments everywhere want to push us towards digital currency.
So when they phase out cash, guess what. You are completely controlled by gov. Bitcoin will be the only way out.
Not only that, when bank systems go down, unless they have every accounts number and money stated every day on paper, you lose all your money.
All the bitcoin nodes can go down for 10 years and as soon as 1 node comes back online, your money is there, it will be there for ever. So all these doomsday scenarios, Bitcoin will be the only one that comes out unscathed.
If you are worried about those, hold a little cash, mostly gold and a lot of bitcoin.
FYI, once you buy a bitcoin (or part), it is yours forever.
You put $100 into your bank account, $90 of that is loaned to someone else.