This is what you call Brand Loyalty

When it comes to Apple, more people are loyal than not, in the sense they prefer to stick with Apple once they have owned an Apple product. This survey [via The Telegraph] of around 2000 iPhone users, for example, reiterates this claim further. 

When asked why they would not consider a different phone 78 per cent claimed they ‘couldn’t imagine having a different type of phone now’. Just over half, 52 per cent, said that they had just been ‘really impressed’ with the iPhone.
— The Telegraph
Apple iPhone 5S (Source - Apple.com)

Apple iPhone 5S (Source - Apple.com)

A couple of points to note from this survey are: what the reason behind this 'blind' loyalty to Apple is? and who owns what model of the iPhone at the time of  this survey? For the first question, the top answer was because they were used to the iOS interface. And the second and third top answers were attributed to iPhone being the best smartphone (at the time of their purchase) and because their friends and family had an iPhone. Now I am not sure if the survey had an option of 'because of the ecosystem' in the list of answers for this question or not. Or what people meant as 'being used to the iOS interface' included the ecosystem as well, but I think another important reason for brand loyalty to Apple is the strength of its ecosystem. You just get hooked to it PERIOD.

37 per cent said it (on why they decided to stick with an iPhone) was because they were used to the iOS interface. Another 28 per cent simply said it seemed to be the best phone for them at the time of switching, whilst 25 per cent said it was due to the fact friends and family members had iPhones and they wanted to retain Apple-specific features such as Facetime.
— The Telegraph

Another interesting question in this survey was on what model of the iPhone they used and 81% of them said they still use an iPhone 5 or 4S or a 4. Only 10% have upgraded to the iPhone 5S! The post does suggests a "don't fix it unless its broken" attitude as a reason for this, but I think people are also waiting out for the iPhone 6 to come out. However I would have at least expected some of the 38% of people who still own an iPhone 4S or older model to have upgraded to an iPhone 5S. 

When asked what version of the iPhone they currently use, 52 per cent said they had a 5, 29 per cent had a 4 or 4S and just nine per cent were still using a 3 or 3GS. One in ten people were using one of the latest two models, the iPhone 5C or 5S. However, the old saying ‘if it ain’t broke, don’t fix it’ could ring true here
— The Telegraph