The problem, in my mind, isn't the absence or rules, it is the plethora of rules in every jurisdiction that are not specifically written with cryptocurrency in mind.
For example, if I create a coin operation and attach something such as artwork, software or other things and have limited terms of service, what happens when you resell your coin. The contract is between you and me. If you sell the coin and the attached items, that third party is not a party to the contract with me. I bear no duties to them.
What if we are in differing types of jurisdictions. I live in a Common Law jurisdiction, but someone in Louisiana, Quebec, France, Germany or China lives in a Civilian Law jurisdiction. The concept of a contract is radically different. Amongst other things, there is no concept of consideration. You also do not have to exchange value to create a contract. There are unilateral contracts. Islamic jurisdictions are highly similar to Civilian jurisdictions but have their own interesting rules. What if the buyer lives in a Civilian jurisdiction and a contract was created there even though no contract would exist in a Common Law jurisdiction?
It isn't the absence of rules that is the problem. It is that the rules are highly varied and potentially mutually inconsistent.
Just a note, cryptocurrencies have existed before, from the time when Isaac Newton was the Master of the Mint until George III abolished "button money." This isn't new and neither are distributed ledgers or smart contracts. They all have their real-world physical analogs, some of which have been in use for six hundred years.
You can find regulations covering every aspect of cryptocurrencies, but they are not written with cryptocurrencies in mind. All you have to do is have a court assert that it has jurisdiction and a new set of rules come into play.
You probably could not do what you are describing because you have ill intent. I would expect most jurisdictions would find your specific description a fraud of some form. Indeed, in Islamic law it would be illegal. Islamic law requires the consideration of third parties who are not part of the current contract to be parties.
If I rent a speaker system for a large outdoor party from you, and we have not considered the impact on my neighbors and included it, then no valid contract exists. Islamic contracts internalize externalities in many cases. The validity of that initial enterprise does not have a mechanism for you to maintain value, you might be required to return all initial funds.
Likewise, there may be damages available in places like Louisiana. There is no concept of consideration, so you must exchange at a reasonable person's understanding of fair value. If you find an old world master in a garage sale, buy it for $10 and sell it for $10,000,020, then you owe the seller at the garage sale $5,000,000.
While U.S. securities laws have applied to some initial coin offerings, to those where it does not apply, no covering, universal set of laws may exist.
If the creators of coins are wise, they have very good attorneys and have written excellent contracts. That does not seem to be the case based on anecdotal comments by attorneys, but hopefully, that is the case and courts will say all is okay.