All that gives a coin their value is the law of supply and demand. It will only be valuable up to a point of how much the buyer is willing to pay for them.
Yes, and that demand comes from a belief system. There is only one thing that ultimately generates demand, and that is desire for satisfaction in the broadest sense. In as much as the offer of that satisfaction is limited, there is a tension between demand and limited offer, and that tension is called "price". We all get great satisfaction from breathing air (so much that if we don't, we die), but the offer of air is larger than the demand for the moment, so the price is zero. There is no tension, so the price is zero, but their is (huge) value (our life depends on it). Essentially, only goods and services can directly help us in getting satisfaction so in as much as they are not in unlimited supply, only they are the ultimate source of "price".
However, we can anticipate, and make plans. We can make plans to provide goods and services where there is a tension (for which there is demand, and still limited or in-existent offer) in order to be able to trade those for other things (goods and services) that give us satisfaction. Doing so increases a demand for production capital, and hence production capital also has a price.
And finally, there are "monetary items" which have little or no actual potential, nor to satisfy directly, or to be production capital, but for which there has occurred an infinitely recursive belief that they have a price. Whenever such an infinite belief system gets hold, the monetary item gets a price (is hence a carrier of value).
Nothing else is needed for this belief system to take hold. Bitcoin is an example. Historically, gold got such a belief system attached to it, and with some coercion, fiat money also gets to have such a belief system.
Now, most people don't like the idea that their precious monetary assets are nothing but "belief", and go and look for its "intrinsic value", but there isn't any. In as much as a monetary item also has intrinsic value (as direct satisfaction, or as production capital), it isn't used as monetary item, or its intrinsic value is much lower than its market price. Gold has some intrinsic value (as jewels to be beautiful, or technical applications), but that intrinsic value alone is much lower than the market price of gold.
Fiat money has only the intrinsic value of the paper it is printed on. And bitcoin has some intrinsic value as "timestamped immutable ledger" but that is much much smaller than the bitcoin market price.
A monetary asset's price is an infinitely recursive belief system: you believe it has value (and are willing to spend goods and services on it to obtain it) because you believe that Joe will accept it later against similar value (and will be ready to give you goods and services for it), and you believe that Joe will believe that, because Alice will believe that, because she believes that Jack will believe it...
Nothing more, nothing less. The belief is what makes the offer (wrt to one's desire to "cash out" and the current market price) and that same belief is what makes the demand (wrt the need to store value for the future).
Of course, you also have to believe that the "token transmission" will keep functioning, but that's about it. All "intrinsic value, developers.... " is similar to "intrinsic value", way, way smaller than monetary belief value.
Will add that I completely agree with dinofelis and kiklo. I have repeated countless of times (and I stand strongly behind Charlie Lee's opinion that a cryptocurrency does not need gimmicks in order to succeed) that people are the ones who are giving the value, not the tech. That is why I believe that everything must be explained in a simpler manner, rather than using fancy roadmaps and whitepapers (which, of course are needed, but you need more than that to bring the average Joe on board). 
