International Law, which above some accord you mention, clearly states that annexing territories is illegal. Anyone that does it must face huge sanctions
In this discussion, that is Turkey, occupying an area in Syria
If you know of more cases like this, by all means you should support sanctions against any despicable country that does that, including Turkey (since were are talking about Turkey in this thread)
And most definitely not invest there! Which is obviously happening as you see with the economic plunge this thread is talking about
You can close your eyes and say "nope" but that is still a fact happening.
There are definitely more reasons, but being bullies and breaking the laws, is for sure one of them