No, they don’t make all that much money. The reason is that blogging wouldn’t fetch you cash in itself. You’ll have to apply for ad monetization and affiliate marketing programs, using your blog as one of the requirements. Afterward, you get paid when readers view your blog posts or follow an affiliate link to a product.
Even with such an arrangement, you can’t expect to make much, as payments often come in their few hundreds. The only way you can make massive profits from the blog is if it’s popular and you sign up for multiple high-paying affiliate programs.