There's a guy who started blogging advice about how to pass the LEED exam
The LEED Professional Exams are administered by the Green Business Certification Inc. for professionals seeking to earn credentials and certificates.
Instead of following his original career path he found that this blogging and ebook writing was making him more money than he could by continuing on in the construction industry, he's now a millionaire many times over.
Pat Flynn.
https://www.smartpassiveincome.com