For us there was no single reason. Certainly not financial or health reasons. We felt we had done it, we felt there was little to do for the kids apart from swim (so nothing at all in winter), we wanted the girls to be educated in the UK although their early years education was wonderful and character forming, we were weary of the expat rumour and backstabbing machine (not specifically directed at us, although we got more than our fair share - it's never ending and nobody is spared), the tired old faces in the same bars full of jealousy and hate for those who don't spend every day in the bars (still evident even last week, the faces are the same but significantly more tired!), the number of people who you have never met who's opinion of you is what someone told them, the tax on imported goods making a little treat a rather big treat, the number of items you can't get in Turkey (but can in Rhodes so it can be done if Governments don't tax to death), the punishing heat of July and August coupled with the cold and rains of winter, the way you have to keep your wits about you every time you spend money and *still* someone does you, the way justice costs a fortune and if the guy you are fighting knows 'someone' you had no chance in the first place, how people in dire financial straits that you help can change from so grateful they could faint to believing that not paying you back at all is an acceptable option (same goes for business), how many hours you spend in Government offices wasting your life away, how many hours you spend in Government offices wasting your life away and it was because they moved the goalposts AGAIN, how many hours you spend in banks wasting your life away, how many hours you spend in post offices wasting your life away, how you get sent all the way home to get your passport whenever you want to do anything, how being Turkish can trump being right, how being aggressive can trump being right, how nobody can take you to buy something without negotiating a percentage of your money while you stand there listening oblivious, how easily a section of the British expats found that a good way to earn a living, how you can get invited to celebrate someone's special day and at the end get your share of the bill, how things like house electric meters stop working and you have to pay for a new one, how "You can afford it, you are British" is justification for trebling the quote, how you have to stand in the searing heat of the market while the guy selling belts asks you to burn it with a lighter to prove it isn't plastic and try and rip it to prove it is strong when all you want is a realistic price and to go, how when you know a waiter and bring him over because someone in your company wants a drink and you tell said waiter he wants a vodka and coke and because you said it they put it on your bill.
I believe you requested an idea of the negatives of living there