Reddit mentions of Byzantium #1 The Early Centuries (v. 1)

1415: Henry's Year of Glory by Ian Mortimer is excellent. John Julius Norwich's series about Byzantium (Byzantium: The Early Centuries, The Apogee and Decline and Fall) are also excellent.

Edit: didn't add any links (3rd attempt).

You are p dumb and also you rely on Wikipedia for knowledge. The Roman (not Greek) emperor renamed the city after himself but to the Greek population until and after the fall of the city in 1453, thirteen centuries later, it remained Byzantium. and that was the name of their empire as a result.

I suggest that you first read John Julius Norwich's superb three-part history of the Byzantines:

https://www.amazon.co.uk/Byzantium-Early-Centuries-v/dp/0140114475
https://www.amazon.co.uk/Byzantium-v-Apogee-Apogee/dp/0140114483/
https://www.amazon.co.uk/Byzantium-Decline-John-Julius-Norwich/dp/0140114491/

Then a useful primary source to start with would be Anna Komnene's Alexiad, written about her father the Emperor and infused with first-hand knowledge of the city of Byzantium and its empire: https://www.amazon.co.uk/Alexiad-Penguin-Classics-Anna-Komnene/dp/0140455272

Then perhaps something like Procopius' Secret History. Then come back and try and tell me that you don't cringe at that time you thought the Greeks called their city "Constantinople".