The niche itself is simply one of the highest-paid blogging niches. So having a crypto-related blog with a certain number of daily readers may guarantee you a good CPM. Other than this, I'm pretty sure good crypto-related blogs always have demand for private ads in the form of banners, buttons, or links. Also, you can sell your membership, affiliate programs, etc. But before thinking about monetization, you should have a unique style and worthy content.