I know there are people who work with demons. But why would you want to? And no, before you ask, I'm not a fluffy "love-and-light" witch who shuns anything and everything to do with darkness. I don't see any foolishness in working with psychopomps or war deities, but... Come on. Aren't a great deal of these creatures akin to the embodiment of evil? And by "evil" I don't mean "death." I mean "evil" as in "more cruel and sadistic than H.H. Holmes, Jeffrey Dahmer, and Ivan the Terrible combined." I understand acknowledging that they exist, but why draw the attention of a spirit that seeks pleasure in inflicting unimaginable suffering on helpless souls? I don't think demon worshippers/summoners are bad people or anything, but why do something that gives you only a slim chance that you'll walk away unscathed? What benefit outweighs these risks?
Everyone has their own taste and their own reason being for doing what they do, it's just like saying "Why practice good magic?" depending on your definition of white magic. Those who "work" with demons are probably highly experienced with spirits and know how to protect themselves and are highly aware of what could happen.
Your view of demons seems a bit tainted. Not all demons are as you describe. Most probably don't give two figs about humans. This is not unique to demons, many spirits don't really care for us either. The world of spirits is vast and you will find those who want to help, those who want to hurt and those that just want the humans to leave them alone.
" there is good in evil and there is evil in good"
For example the Greek gods. They are good they did many things but people ignore that most of the male gods are rapist and cheaters. Most people thinks that's "evil". You can ask a deity for the same things for a demon maybe like love or power. And if you summon or encounter a deity, demon, dragon, fae, and so on they all want respect, they want the truth, and if you summon them they want a purpose. Sometimes you can get on the bad said of a demon, deity, dragon, and so on; they all would make your life uneasy. Too me they are all the same.
"Never judge a book by its cover"
Do some research. There is a demon that protects children( I forgot the name of that demon) and that doesn't seem evil at all.
it also depends greatly on one's definition of demon, and by what perspective they are considered as demons. For example by Christian perspective, any being that is not of the established heavenly host, and/or any being that operates outside or counter to the christian perspective of God tends to be labelled as demonic. So naturally not all such beings would be by default 'evil'.
others might base it on the appearance the being uses to represent itself. IE; some would label a being that has hooved feet and/or antlers as demonic. Or one that is winged or scaled or red skinned or otherwise of an appearance that is decidedly non-human or fearsome. Again, this would leave them as not necessarily evil in deed or word.
Then there are entities who are genuinely malicious in behavior, seeking to take energy from others, fostering a desire to dominate, possess, or control and often using a person's beliefs and vulnerabilities against them to do so. And these can be of any form or origin, including (and, actually, quite commonly) previously human.
Honestly I consider the term 'demon' to be a human construct based on the perception of the individual. And so working with them is likewise a matter of that same perspective. That said, there are definitely malicious individual entities out there who are out for their own gain. Much like people. they can be up to mischief, or maligned, or outright malicious and hateful.
Also, As energy is largely formless, its appearance to someone connecting with it is subjective to a person's interpretation of how that energy feels and to an extent how that energy projects itself/wants to be seen as. I imagine this is why more often than not, negative entities tend to be felt or seen as dark shadows, black masses, or in imagery that is frightening to that individual. So it is not that often that a 'demonic' entity actually appears in a demonic form.
As stated above, your view on demons does seem a bit tainted and biased, and not every entity has the best intentions either.
Some entities are more difficult to work with than others, and everyone's experiences when working with different, or even the same entities, are going to differ. I also find that when you approach an entity with a certain..let's use the word attitude, or expectation, then they will assume that role and act or appear in how they are expected to.
Then there's a culture's definition of demon. A Tibetan demon would be very different from a Native American One. Ande as has been stated already, not all demons are bad. I'm not sure on this, but isn't Kali (Hindu chaos goddess) a demon or control demons?