I'm Turkish and i live in Ortaköy neighborhood in İstanbul where attack took place. That night club is just 1 km away from my flat.
Turkey is a secular country which is leading by democracy, rare amongst Islamic countries thanks to our savior Mustafa Kemal Atatürk
Firstly, we fight against more than 1 terrorist group. Turkish people have witnessed dozens of bombings/suicide attacks/ambushes/outpost raids in 40 years. After all, we got experienced and being conscious which terrorist group aims what and what separates them.
1) PKK(Kurdish Rebels) mainly targets soldiers and policemen. Kurds are vast majority in south-east of Turkey. They want to separate south-east part of Turkey and put Kurdistan on map. PKK's first armed action was in 1984. Imagine you guys in U.S.A dealing with El-Qaida for 40 years. PKK killed moreover 30000 Turkish citizens since 1984. 3 weeks ago they killed 34 policemen plus 10 civilians by suicide attacks. PKK and their extensions in Syria(PYD-YPG) are supported by USA and western countries. Their headquarter is at mount Qandil in IRAQ, 300 km. away from Turkish border.
2) ISIS targets anyone who remains standing on 2 foot literally. They burnt alive 2 Turkish soldiers and published video records on internet. I, myself as a Muslim Turkish male, frankly can say this; islam which ISIS introduces all over world is not the real islam itself. They are just barbarians not related to islam even 1%. They took 35 lives 1 hour after midnight in a night club. Why did they do this ? Simple, in their mind muslims are not allowed to celebrate new year, its a christian tradition and a sin for muslims. Someone should teach them 24th of December is a special day for christians and new year eve is totally different matter.
3) FETÖ. Fetö is the short term of "Terrorist organization of Fethullah Gülen". Mr. Gülen lives in USA and indeed his cultist movement were friendly with government. With the non-conscious support of Tayyip Erdoğan, they became so powerful across all government agencies in late 90's. Since 2014, they didnt want to share power with Erdoğan and attempted to overthrow him. Last week, one of FETÖ agent killed Russian ambassador in Ankara, capital city of Turkey. More details ->
https://www.theguardian.com/world/turkey-coup-attempt
I wish one day we have peace same as western countries have. Middle-East is the place where humanity experience hell on earth. I wish human life would cost much more than nothing in my country. I wish we could invest more in technological improvements, health care, education and fine arts instead of military.
P.S.: Sorry for my English, i tried to explain complicated things not in my mother tongue.