Hi I want to share my personal opinion about this. The problem here imo lies in the majority of the population don't know really well how money works in our economy.

What makes a currency a source of prosperity?

• Must ease the transaction of assets: for that it must be easily accesible, used worldwide by any person and be easily exchanged (gold does not fit in this rule since it has a limited quantity)
• Its market capitalization, ie total volume of currency, and its rate of issuing by each country or entity must be tied to some form of quantifiable asset owned by the agent wanting to issue the currency: here lies the elephant in the room, what most experts think is the root of the cyclical economic crises the world has; the Fractional Reserve Banking system that allow the banks to only have a 10% of the total of deposits backed by cash-on-hand available for withdrawal. This extends to loaned money so the 10% rule can be reapplied to issue 10 times more money than the bank has over and over again. A recent example of the implications of this system is the intervention of the Bank of China to save its economy by lowering interest rates on its loans. Companies on the verge of bankrupcy can ask for loans at low interest rates to rebuy their stock and inflate its price artificially without any real growth of the company. The stock market will reflect an economic growth but this will be all fake. This, in my opinion will lead to a bigger economic meltdown when those loans are overdue.
• Must be widely accepted and trusted: gold is falsifiable and difficult to track down, you need some form of verification of the metal and when you need to make big transactions it becomes a problem to check every ingot. The only solution that gold contribute is that one mentioned before of representing a quantifiable asset to back currency issuing, for example if the reserve banking system would be abolished. A better quantifiable asset would be an accurate measure of a country industrial power, enterprises, natural resources, but I admit gold (as diamonds, gems or any other scarce resource), in this case would be more comfortable to measure than a country real assets and resources. But imagine we use diamonds, South Africa with its diamond mines would be allowed to issue much more currency than the rest of the world when its growth is not much bigger if not much smaller than other countries. For that reason it is better to establish an inventory of the total of resources, enterprises and industries available to each country or corporation as a mean to establish its assets. Any other way is opening the door for speculation and repeat past mistakes. What leads me to my next point.
• Must not be object of speculation: as I mentioned before when you tie the market cap to an accurate measure of a country assets you can't create artificial scarcities or flood the market with stocks to drive the price down (in this case the trackeability helps to fight this as well). You know something is wrong in the market when you can buy contracts for several tons of aluminum when you aren't going to use that metal for anything productive, just to speculate on the price. Is famous the story of Wall Street brokerage firm that bought several thousands heads of cattle to speculate on their price but forgot to sell them and they ended paying more than what they invested to rent a place to store the cattle and feed them. To avoid speculation a currency with a trackeable source is specially useful since it allows to know if the buyer is an enterprise in need of the resource or a speculative party. Gold is difficult to track and our paper money can be tracked but needs intervention by the government. Some cryptocurrencies allow a easier tracking by normal citizens and even its automatization and implementation of more security measures as they are open source and constantly evolving, adapting to the new needs of the population.

As you see cryptocurrencies comply with most of these requirements and if not they can evolve and address those needs. Gold only use is to give some form of material backing to the currency issuing but is a lacking way to quantify value as mentioned in the post. The only flaw of cryptocurrencies is they need some sort of computational power, a physical support open to attack or malfunction but that happens with any form of currency we choose as anything can be stolen. When cryptocurrencies improve the redundancy of their storage wallets and the majority of the population learn to use it the malfunction flaw will be addressed.