They are going to have major problems from their attitude. What happens when their incandescent light bulbs are no longer available? They are going to need compact fluorescent bulbs that give off something that vaguely resemble light, and plenty of aspirin--or a LED (skip the aspirin). The LED is more expensive but lasts longer. I also noticed around 3-5% drop in my light bill, in the middle of summer with the air conditioning going and the average temperature the same, per month since using LEDs instead of compact fluorescent. And I don't use them all that much. In an energy crisis, my "materialism bulbs" are going to be the clear winners. Yes, they put out as much usable light.
And, during the coming energy crisis (which will happen at latest once the Iran-Israel war gets going), rolling blackouts are expected to be more common. The witlesses might think it's excessive materialism to have a generator. Or, suppose you get 3 or 4 battery chargers that can handle 4 D batteries, along with another that can do 16 AA or AAA batteries at a time (or 2, or 3), and tons of low self-discharge batteries. Brother Hounder is going to claim you are not relying on Jehovah. Then, you get a major storm and have plenty of charged batteries. You put them in your fancy LED lanterns and headlamps you bought at Battery Junction, and you can read your materials. While Brother Hounder has nothing but a cheap flashlight with 2 D batteries that he can't see worth anything. Or, rolling blackouts that frequently disrupt the evenings hit. What now? How are they going to study if the lights are out? And, who is going to be most valuable at the Kingdumb Hell when it goes pitch dark? Someone that didn't prepare, or the one "materialist" that came with a strong headlight?
Remember, these aren't even luxury items. I got nice batteries and numerous nice battery chargers that I am sure Brother Hounder would have a stroke if he saw. I got nice LED light bulbs that are really great with electricity usage. And who is Brother Hounder going to thank when my LED lights make the difference between a close call and getting rolling blackouts?