Did essential oils not work for you?

So my sister and sister-in-law are obsessed with using essential oils for everything. I have used them before for various things and they have never worked for me. I fail to believe I am immune to the effects of essential oils, but that it is more likely the placebo effect is working on me. Even when they tell me of all their miraculous experiences, it's something like, my daughter had a cough for a week then I gave her the oils and in two days it disappeared. Now I am thinking, In 9 days the cough probably just went away on it's own, but not them. They feel like it was all due to the oils. The thing that really grinds my gears is that when the oils don't work, which is often, they never doubt their effectiveness, but they go and buy more at $20+ a pop. The medication in the pharmacy to cure whatever ails them is probably cheaper.

Anyone else with the same thoughts?