Demons can't invade your life at a whim. They are either given permission (through sin/occult/otherwise) or God using them for his purpose (Story of Job, Thorn of Paul)
Men are given dominion of the earth. Demons are basically squatters until they get tossed into hell. Unfortunately some people don't recognize the authority given to them by God and Jesus. Incorrectly letting demons have legal ground to do their bullshit. Usually through false gods and paganism and folk rituals.
Turn to Jesus while you still have the chance.
https://www.youtube.com/watch?v=xbLMGZzPW40 