>> The people behind bitcoin can punch up as many bitcoins as they want with a few clicks on a computer.
The algorithm used to generate bitcoin involves the solution of a mathematics problem which was successfully designed to become progressively more difficult as the number of bitcoins approaches the predetermined limit of 21 million. (17 million have already been created.) Generating bitcoin now requires expensive, specially optimized computer hardware and lots of electricity. In fact, unless you have some way of generating electricity at a fraction of what Hydro Quebec currently charges, your electric bills alone (never mind hardware purchase and maintenance, storage space etc.) would exceed the market value of the bitcoin produced at present.
>>One day they will fold up shop.
There is no individual or organization with that capability. There are thousands of computers which each maintain a record (blockchain) of every bitcoin transaction. One would have to hack those thousands of computers simultaneously to alter those records.
>>Where and how is bitcoin backed and guaranteed?
Since the mid 1980s, Venezuelan currency has been devalued by a factor of more than a billion. Bitcoin is also a currency - a medium of exchange. Like the Bolivar, it will be worth nothing if nobody wants it. Canadian Tire money will be worth nothing if that company closed its doors tomorrow. In the case of bitcoin, there is no company to go out of business, but it would be destroyed if somebody finds a way to destroy the internet.
Nobody backs it against gold or any other commodity. However, the same is true of the US dollar, which went off the gold standard almost 100 years ago. It's a lot easier and cheaper for the US government to print paper dollars than it is to generate bitcoin. Unlike the US which can and does create money rather freely, the total number of bitcoins is limited by the algorithm which generates them, so, while someday it may suffer the fate of the Bolivar, it won't be because too many are in circulation.
