Is relative. The thing with well known brands is their stuff has resale value (and they probably know this) so its not quite as expensive as you might think to keep up with the latest branded kit (unless it is your first purchase).
Im using a Galaxy Note 3 which is a very expensive phone. Its served me well so far and apparently it will be getting Android M! In fact its such a good phone I havent felt compelled to upgrade at all for ages (I love my tech and I suffer from severe technolust from time to time).
Ive had this phone since launch (September 2013, happy birthday phone!) and I suspect ill have it for at least another 2 years...or until something compelling comes along!
I sold my Galaxy Note 2 to buy this phone so I probably ended up paying around £100 for it. The Note 2 I got by selling my Galaxy Nexus and so on...right back to my Motorola Startac in days of yore. Which I got as part of a contract.
I miss that phone scorching my skull.
I have no particular loyalty to Samsung they've just had a good run up until the Note 4. Not quite sold on the Edge or the S6.