If you do, I think it should be a very brief, single paragraph article like 100 words or less that simply identifies what Bitcoin is.

I wish rather than deleting the article, they put a length restriction.  If something is not famous enough, there could at least be a stub article identifying what it is.  I often come across annoying red links of things that Wiki ought to at least have heard of.

The article could be as simple as something like:
"Bitcoin is a peer-to-peer decentralised /link/electronic currency/link/."

The more standard Wiki thing to do is that we should have a paragraph in one of the more general categories that we are an instance of, like Electronic Currency or Electronic Cash.  We can probably establish a paragraph there.  Again, keep it short.  Just identifying what it is.