My NIP-05 is Jordan@acceptcrypto.org because I run a website called nostr:nprofile1qqsfmt5xeuaeaxdseegdu62errxs2altdl2m24ug3kdjrel9dlte38gpz3mhxue69uhhyetvv9ujuerpd46hxtnfduq3vamnwvaz7tmjv4kxz7fwdehhxarj9e3xzmnyqyw8wumn8ghj7mn0wd68ytfsxyh8jcttd95x7mnwv5hxxmmdrmyzsp which is about encouraging, and promoting Bitcoin, and Cryptocurrency adoption for payments.

Bitcoin is a Cryptocurrency.

It is meant to be used as a medium of exchange but yes, you can also save it too.