Gerard:
This is an interesting question and it raises a number of philosophical issues. First, what is meant by the word 'scam'. I take this to mean a transfer of funds from one party to another on the basis of false contract. At the highest level, scamming is an important aspect of human activity and scams will always capture incentive in any system of money.
Central to this problem is the question - is cryptocurrency money? What is money? Is there a difference between sound and unsound money? At its core, money is a property of the human psyche. The mind perceives value. There are probably astroids with huge concentrations of precious metals moving in the blackness of interstellar space, and yet people live and die for gold.
Is gold good money? Most would argue yes, at least as a store of wealth. Here on earth, gold takes effort to obtain. One must go out and mine gold, which requires investment of time and resources. The gold itself "proves the work" (PoW) of the miners and it justifies their investment. For humans, gold proves work and establishes access to resources. A unique property of gold is that it is somewhat decentralised. There are gold mines all over the world - in South Africa, Australia, Brazil, Russia and many more. This makes gold relatively censorship resistant. Furthermore, gold supports peer to peer transactions. Any debt or transfer of ownership can in principle be settled in gold quietly and quickly. At the highest level, international banking cartels settle debts ultimately in gold when fiat solutions are not available.
Replace 'gold' with 'bitcoin' in the above paragraph and you will find some very interesting results .
Since bitcoin is a "crypto" and bitcoin is a virtual form of gold, then either both are a scam, or neither is a scam. Generally, gold is not considered to be a scam. Indeed, it is the most stable store of value. Bitcoin is also a stable store of value, though it offers the strategic benefit of being digital. It is much more censorship resistant and it is much more difficult to seize than gold. Thus we have at least heuristicly arrived at the conclusion that bitcoin and gold are not scams.
Now let's fast forward to the industrial revolution. New metals are being mined and new alloys are being created. All of these promise value in some way as they beg to be adopted in some new technology. Then comes the growth of modern finance capital, which provided more abstract ways of representing wealth via "contracts". These ever expanding layers abstraction and wealth representation allowed for more flexibility, and the contact author is obliged to ensure that the contract is not dishonest. The contract must accurately represent reality, and there can be no gerrymandering of the data. In other words, the issuer is responsible for verifying that the contract is not a "scam". Naturally, Murphy's law suggests that not all contacts will be honest, some will be scams. Commerce is a Byzantine environment ...
Again we see the development of parallels to what is happening in the cryptocurrency space. We have moved beyond digital gold and into a new era of contracts on the blockchain. By this logic, some of these contracts are scams insofar as they are dishonest contracts. They do not represent reality.
We note also the analogy of the discovery of new metals during the industrial revolution, and that these metals themselves were like gold. New metals such as chromium and vanadium became valuable as their properties were found to be useful in steelmaking. In the cryptocurrency space, these metals are the new blockchain protocols, like ETH and ZIL. Both are precious resources, representing and securing contracts via hashing power.
In truth, the value of bitcoin is a deep and interesting thread of philosophy. It taps into the root of who we are and how we interact socially. It is primordial and yet it is sophisticated. With the advent of new technologies, the concept of wealth itself is liable to change. Cryptocurrency is an experiment. Enjoy the ride.