Can I self-learn by reading all books in Bachelor/Master degree syllabus?

Yes. However, oft recommended books are classics from the ancient times and in them days people weren't in the habit of writing directly to the students (for the most part). Learning from stuffy old books builds character, but robs you of your time.

Instead, pick a subject. Say, abstract algebra. Input this query into the search field on Amazon. It's spits out 100 or so pages of book titles (each page probably has 10 or so books - haven't checked). That right there is a treasure trove. Methodically check through each book. Each book will, in turn, have even more books in the suggestions area. Clicking on any of them will lead down the endless rabbit hole. Going back to the search field and slightly tweaking the search query to, say, "group theory" or "sylow theorems" will result in yet another wildly different list of titles. This shit grows combinatorially :) Along the way you'll come across spectacular books you weren't even searching for (say, textbooks on stats, category theory or measure theory or algorithms). Don't forget to search by date and other parameters, too, as there is a constant churn of new titles. This will introduce you to a ton of phenomenal stuff that never get any mention anywhere (you'll mostly hear about tired old cliche titles). Check out the interesting titles on libgen.

Other sites where you can learn about old, current and upcoming books of interest are Cambridge Press, Springer, MIT Press, MAA etc.

I had to write this in a hurry and forgot a ton of what I was going to say not to mention most of what I typed up above is probably hard to parse as I didn't edit this whole thing. The bottom line: do not depend on the classics. You can always do better and you'll save a lot of time.