In short, it is we, as an aggregate whole, that does so.
As long as enough people believe something has value, it will have value.
There are stocks with companies long since dead, that are traded to this day.
There are trading cards wherein certain cards can be traded for hundreds, if not thousands, despite being bought for less than 10 and being made for less than 1.
There are digital items than can be obtained for virtual avatars that are purchased frequently and often, despite having no apparent tangible value.
In the history of our species:
We began with shiny rocks and minerals.
We shifted to fancy paper.
We have started on the path towards digital.
The transition from one stage to the next is mostly due to risk and convenience.
Gold is heavy, risky to transport, and is difficult to utilize for small transactions.
The transition to paper started with the advent of coins.
Paper is light, easy to hide, and convenient for local transactions. But, dealing with change is messy and due to necessary rounding often imprecise. International transactions are also slow and expensive. The transition to digital started with the internet and can be attributed to online banking and credit cards.
Digital, utilizing the blockchain technology, is safer than paper and more private. It can be used for any type of transactions and is faster, cheaper, and more secure than the alternatives. It is not perfect. In many ways, it is like an automobile when it was first invented, with a horse being superior and more practical. But, like automobiles, it has the potential to overcome the shortcomings through constant development. In the digital realm, progress occurs at speeds far beyond that of the normal world. It will take time, but it won't be long before Digital take over.
Those that stand in the way of progress, may succeed for a time, but they are human. As long as the vast majority desires a change and is willing to fight for it, they will obtain it. Never forget that the current system is flawed, inefficient, and corrupt. Be patient, invest wisely, hold strong, and have faith. We are on the verge of a new age in the financial world, let our tale be one of riding into glory and returning triumphant, instead of one of sorrow for missing out on a fantastic opportunity to realize our fortunes.