@BldSwtTrs:
Common nouns are not capitalized while proper nouns are.
Common nouns refer to a
class of person, animal, place, idea or thing, while proper nouns refer to a
specific instance of that class. For example, "month" (not capitalized) is a class of time periods approximately 30 days in length, while "January" is a specific instance of that class (capitalized). Similarly, "man" (not capitalized) is a class of humans that have a Y-chromosome, while "Peter R" refers to the specific instance of a man who is writing this post.
The word "cryptocurrency" (common noun) refers to the class of electronic, decentralized, digital currencies that we like to endlessly discuss, while "Bitcoin" (proper noun) refers to our favourite instance of that class
The word "bitcoin" (common noun) refers to the class of currency tokens exchanged on the Bitcoin network. I could name one of my bitcoins "Henry" if I wanted to refer to that bitcoin specifically.
To answer your question, when we say "Bitcoin network" we mean the specific network of miners and nodes that are building the Bitcoin blockchain, and so we capitalize (it's a proper noun). Similarly, when we say "Bitcoin blockchain" we refer to the specific blockchain that starts with the Satoshi genesis block and contains more proof-of-work than any other competing chain, and so it is also capitalized. (One could argue that it should actually be "Bitcoin Network" and "Bitcoin Blockchain," as both terms could be considered proper nouns in their own right).
