Many factors.

Primarily it is because of nationalism and ever since the founding of the Republic of Turkey, great effort has been made by the state to suppress Lazi and Kurdish and other non-Turkic indigenous languages, all the while promoting Turkish language across society. They still do this to this day with regards to Kurdish, an Iranian language.

On top of that, Turkey is not on good relations with most of its neighbors. All the neighbors dislike Turkey, for various reasons, so you don't hear often of Turks learning Armenian or Greek or Bulgarian or Georgian for example...

Turkey also has a bad view of the old Arabic script, so Arabic and Farsi languages included are viewed as inferior and in general there is a patronizing view of the Arab world.

Relations with Europe and "the West" are not good either, and there is a great deal of Westernphobia in Turkey, so popular languages like Spanish, French, Italian, German, are left out.

My dad is turkish and speaks Italian and english. Many turks learn English in school and my cousin’s daughter is also learning mandatory German in school. I met many Turks who also speak Russian.

There aren't many people from European countries in Turkey. So we don't need to communicate in foreign language. Turkish is enough for most of the people. It is necessary to learn a second language if you work internationally.

Because our educaiton system so wrong about English or other languages, generally our english courses focus on grammer and all students want to use the grammer very well and they dont focus on speaking also most of Turkish guys have not self confident when they start to speak with foreign people they think that if they make a mistake people will laugh or say bad things about their English at least i was think like this but i have found a good language course they focus on only speaking and they have many foreign teacher and most of them from th US and they dont speak Turkish in the classes evden if they speak Turkish and they want all students to speak English better and they push the students if you are lucky you can find a good English course in your city but generally we have not

bence iki sebebi var. birincisi utangaçlık, bizim erkeklerimiz başka türlü, kızlarımız başka türlü utangaçtır. ikincisi de okullardaki eğitimi yetmiş yıl önce programlayanlar bunun için bize tuzak kurdu. türklerin yabancı dil öğrenmesini bol bol gramer öğreterek ama listening, speaking, reading ihmal ederek engellediler.