Why? Suppose that you read a concept in a freshly published book. It may be a perfectly valid concept, complete with extensive back-testing. That’s fine. But now suppose that you read a concept in a book published 100 years ago, and as you study it, you see that the concept has continued to work since publication.
You have just learned a concept with a 100-year long track record of success!
That’s invaluable. And there are many such concepts. Many. Human nature does not change. People today trade stocks exactly like they did 100 years ago. The same patterns keep repeating over and over.
Only a tiny percentage of traders make money in the market. You can join that elite group much faster if you study the classics.