Let's say I've read many books and became an expert in a subject area. If I share my knowledge on my blog with details and start to earn some money, would I infringe upon the copyright of these book authors?
Copyright protects original works of authorship [...] Ideas and discoveries are not protected by the copyright law, although the way in which they are expressed may be.
So that means that information (ideas) themselves aren't covered under copyright law, just the way that information is expressed (including but not limited to the exact wording). It's the difference between copying something verbatim versus presenting similar ideas in with your own wording and expositional style.
As a rule of thumb, imagine turning in your blog article to your high school teacher as an essay. Would she give you a zero for plagiarism or large swathes of copied content? If so, it's probably copyright infringement.
Also, read up on the copyright.gov page about fair use, although that might apply more if you were critiquing the original source rather than presenting the ideas from it.
This answer reflects my interpretation of US law as a layperson, I am not a lawyer nor giving legal advice, and I will not be held liable.