<only for people who mastered more than 3k English words and have experience of reading at least 1~2 English books.>

1. In the realm of hungry ghosts - by Gabor Maté

https://annas-archive.org/md5/d43262bef1512331251c476c8b411600

https://www.amazon.com/Realm-Hungry-Ghosts-Encounters-Addiction-ebook/dp/B07CJNMY2H/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=&sr=

--> Written by a doctor who had cared for drug addicts. Very moving and showing a very deep philosophy about people suffering from the loss of love in their early childhood.

2. Progress and Poverty - by Henry George

https://annas-archive.org/md5/f726c4146866f82ac7ccdbb811f94b8a

Amazon link. 

--> Very famous book about why the price of land goes up more rapidly than the cost of labor and money. Provides very good insights about our economic realities.

I recommend you to read these books at least 2 or 3 times. One more peripheral thing I want to inform you is that referring to English-English dictionary should be more helpful in improving reading skills. I suggest 2 dictionaries. Oxford Advanced learner's dictionary and Merriam-Webster Learner's dictionary.