Let me hit the nail without wasting time.
People still spend a lot of money on high end phones because of "quality assurance".
It should be noted that quality assurance is very expensive in manufacturing. This is in terms of:

1...Health:
High quality built screens to prevent eye damage over time.
Well designed audio system to prevent ear damage over time.
Low electromagnetic radiation that could cause cancer.
Safe battery design to prevent explosion that could result to severe injuries.

2...Serviceability
They can easily be fixed through there service centres by competent engineers
The parts are easily available in case of any damage whatsoever to the device.
Good software support online to enhance your device or fix any software related issues.

Optimization and performance:
The processors used are powerful
and are optimized to prevent over heating that greatly drains battery
The os and user interface are designed for simplicity of use to make u smart and achieve your work faster. All these enhances device performance.

Built and durability :
The manufacturers uses quality hardware to build the device for high lifespan or durability
The hardwares used ensures device does not fade or break easily.

style:
they come with uniqueness in design that draws a sense of appeal to buyers.

taste:
Better soup na money kill am. i will not say more than that, if na lie ask lala . Some people always wana spend on better soup. They got the cash and you can't just stop them from enjoying better soup.

Prestige and class:
Some people love to feel awesome and respected
as such they show off expensive device and believe me it works.

They save time and life:
Pls do some research on health technologies through iphones, you will understand better.
With minimum system lag you beat time getting output from your device. System lag can make u waste time and deny you an opportunity.

Peace of Mind:
Psychologically, whenever people think of the advantages they have it makes them happy. Knowing you own a device with numerous advantages mentioned above gives u joy and make you feel satisfied, no body want to be sad whatsoever,sure!

Egbon Hmmmmmm

OP, you are so right.

Is that why Samsung phones are over expensive

Let me break it down for you, so you'll stop deceiving yourself.

1...Health:
High quality built screens to prevent eye damage over time.
If there's any eye damage caused by phone screens then you can be rest assured that both high and low end devices affect you the same way, the main differences between them are the proprietary technology applied in the high end stuff e.g Samsung's Super Amoled , or Sony Bravia.

Well designed audio system to prevent ear damage over time.
Same as above

Low electromagnetic radiation that could cause cancer.
Phone radiation are not known to cause any harm, and seeing as both high and low end devices operate at the same frequencies, if there's any damage they are both guilty

Safe battery design to prevent explosion that could result to severe injuries.

I am more inclined to agree with you on this one, but i've heard more stories of Samsung or Apple phones exploding than any other OEMs


2...Serviceability
They can easily be fixed through there service centres by competent engineers
I agree somewhat

The parts are easily available in case of any damage whatsoever to the device.
I also agree with this

Good software support online to enhance your device or fix any software related issues.

Definitely an advantage

Optimization and performance:
The processors used are powerful
and are optimized to prevent over heating that greatly drains battery
The os and user interface are designed for simplicity of use to make u smart and achieve your work faster. All these enhances device performance.

Now this is a load of rubbish, on over-heating, devices from high end OEMs overheat all the time e.g LG G3, it was famous.
On UI design, that is subject to each user's opinions and needs, until recently Samsung's TouchWiz was well hated in the tech community and for good reason, same goes for Sony and LGs UI, HTC's Sense UI was the only one that got a little love in the Android circle, as for iPhones some people find iOS too simple and limiting.
Built and durability :

The manufacturers uses quality hardware to build the device for high lifespan or durability
The hardwares used ensures device does not fade or break easily.

Can't agree with you unless you're talking about Nokia here, personally I know Samsung and HTC phones as fragile devices

style:
they come with uniqueness in design that draws a sense of appeal to buyers.

Nope, even low end OEMs can design a really good looking device, case in point Tecno's Camon C8, Infinix Note 2, Innjoo Halo, they all look good while being relatively cheap,
And you may have forgotten Samsung's design blunders with the Galaxy S3 to S5 that looked and felt cheap compared to other Manufacturers, and Sony's devices don't get a lot of love either design wise

taste:
Better soup na money kill am. i will not say more than that, if na lie ask lala . Some people always wana spend on better soup. They got the cash and you can't just stop them from enjoying better soup.

ehm

Prestige and class:
Some people love to feel awesome and respected
as such they show off expensive device and believe me it works.

My Millionaire uncle uses a blackberry curve 2 while his banker son uses a six year old Sony Xperia, on the side of this coin my student neighbor with her tear tear pant uses a Samsung Galaxy Note 4, my other borrow borrow neighbor uses a BlackBerry Z3, draw the conclusion yourself.

They save time and life:
Pls do some research on health technologies through iphones, you will understand better.

More rubbish, none of the health tech on iPhone were invented by Apple meaning you can find them in other devices like Xiaomi devices for example, and these health apps are hardly the concern of the average Nigerian

With minimum system lag you beat time getting output from your device. System lag can make u waste time and deny you an opportunity.
If I wanted to use a device with minimal lag I would buy a N15,000 Lumia

Peace of Mind:
Psychologically, whenever people think of the advantages they have it makes them happy. Knowing you own a device with numerous advantages mentioned above gives u joy and make you feel satisfied, no body want to be sad whatsoever,sure!
People are never satisfied my dear, that's why they're always buying the latest version even if there's no advantage to doing so.

Gionee, tecno and co have made everything easy, you don't have to spend all your hard earned money on gadgets

mosjames:
Gionee, tecno and co have made everything easy, you don't have to spend all your hard earned money on gadgets

I hear you oh

mosjames:
Gionee, tecno and co have made everything easy, you don't have to spend all your hard earned money on gadgets

abi oooh I agree with you