If your friend meant daemon, a general greek term for higher spirits, than yes, in an animism based belief system (that everything has a spirit/life force), all magick is spirit and we have spirits around us that guide us.
But "demon" in the definition of "infernal spirit"... No. Only those that specifically seek out to work with infernal spirits work with infernal spirits. Their are plenty of magicians, witches and the like that work with angels, nature spirits, deities, etc. and have never worked with infernal beings.
When working with spirits of any sort, yes, there is generally always a trade but experienced practitioners that are familiar with the spirits they work with know exactly what that spirit likes and offers it (be it incense, tobacco, food, drink (alcohol), blood, ceremony, etc). It is inexperienced practitioners that ask, receive, and do not give proper offerings that end up getting hit with a "price" they didn't anticipate. That's the metaphorical lightening bolt smiting you for being stupid.