We have tags for cryptocurrency and bitcoin. Presumably, the bitcoin tag would be used for questions that are specific to Bitcoin only, but not to any other cryptocurrency. I understand that Bitcoin is about as old as our site, and when the tag was created, there was no other cryptocurrency. However, in the context of our site, I would think that anything on-topic here regarding cryptocurrency (taxes, investing, etc.) should apply to all cryptocurrency. Any question that is specific to Bitcoin and not to the other cryptocurrencies (mining, wallets, network, etc.) is probably not on-topic here (but may be on-topic on bitcoin.SE).
Done. Although, in my ignorance of not knowing precisely how the 'merge' command works, I think I killed the bitcoin tag and replaced it with cryptocurrency. Which is probably fine as I gathered from your comments, i.e. a truly bitcoin-only question should get sent to other stack. Kind of how we often use "kleenex" when we mean "facial tissue", and it's wrong, we should keep generic questions distinct.
By the way, no need to vote on these. If there were a strong reason to reject a merge request, we'll let you know. 99% of the time, they are logical and done.
I have already suggested this synonym, and if you have a total answer score of 5 or more on cryptocurrency you should be able to vote on it here: