Most of the investors in Turkey come from the Gulf area; countries such as Saudi Arabia, Iran, Africa, Egypt or Qatar.
These are foreign people seeking a more established and secure country, but also a country with a familiar culture.
Most people in Turkey are Muslim, which makes investors from Arab states feel closer to home. Rather than tax or fiscal reasons, one can easily argue that those people want Turkish citizenship for reasons of security, society and culture. Turkey is ideal, because it is closer to Europe than the Middle East, but with a relatively similar culture.