Why use endnotes in writing a short essay for the web. Make links please, so that the reader can go directly from a statement of yours to the reference that helps to confirm it, so they can judge the quality of your source, and read more conveniently for themselves.

You did some good learning here, but not knowing what you didn't know, you took a metaphor for reality.

A smart contract is simply, as Chris Ferris said in his presentation at our conference, a stored procedure in a database. It's not a replacement for contract law, anymore than the hundreds of such stored procedures you trigger every day, in databases like Facebook with which you interact, and in which algorithms are started as a result of data access or searching. "Smart contracts" are not an innovation in that sense, but an analog of an existing software style "ported" to the new software style that is blockchain.

Worrying about malicious programming (which is poorly described by the word "hacking," which has another and more valuable conflicting meaning) is sensible with respect to any form of software that moves money. But worrying about material that is cryptographically secured against tampering, while sensible because all software has exploitable failure modes, makes sense only after one has worried about tampering with all the critical data that isn't cryptographically secured, and whose theft or modification causes big social harm every day.

In short, your learning was a little too narrow for the conclusions you drew from it. The greatest asset of the expert is a firm grasp on the obvious, which you don't quite have yet. The best route to improvement is to widen the focus on your learning about blockchain, so that you can describe not only correctly but in correct proportion what you have learned in relation to the concerns of a reader who has not followed you in your learning yet, and will do so through the next draft.