In Pursuit of Blockchain...

I am actively trying to understand exactly how blockchain technology is "secure."

According to a Wall Street Journal explainer blog, “A blockchain is a data structure that makes it possible to create a digital ledger of transactions and share it among a distributed network of computers."

If the there is a digital ledger of transactions, and this ledger is shared among a distributed network of computers, then by its own definition, how can it be secure?

Here is my concern, if enough people become convinced that blockchain is secure, they will not resist financial institution's plans to do away with cash. Once cash is eliminated, there will be no way to conduct any kind of transaction without it being reported directly to a central authority.

Once this occurs, the central authority will have absolute power over each and every consumer choice it chooses to regulate.

I believe that the people who support blockchain are sincere and wish to provide a platform for transactions that is secure and free from monitoring by undesired individuals or entities; this is a worthy goal. I just cannot get past the fact that computers, routers, servers, and networks are traceable and if you are using any of these tools to conduct business, then a trail is being left behind that someone, somewhere, sometime will be able to trace, manage, and control.