What's a luxury people don't realise is a luxury?

my mother always says that everything other than a home, food, water and human interaction is a luxury. she says with that mindset you learn to appreciate everything.
but to answer what u asked for: electricity. the absolute brittleness of the electric system, especially with what is going on with dismantling public infrastructure over in the US, it's a great reminder that as normal as we see electricity, it's a luxury dependent on the duty and diligence of tens if not hundreds of thousands of workers all around the world
- That's 100% true and the sad thing is they're not workers that are valued. They're blue collar workers that we'd grind to a halt without

Citizenship in a country that's not trying to kill you
- Yep!!! I'm lgbt I literally have to check laws of countries I go to before I go on holiday. I at least don't live there!

Clean water, and sanitation. Most places in the world does not even use toilet paper.
Also biologics medication to treat many diseases that don't have medications that were effective before, like psoriasis and eczema, topical had only a temporary effect before it causes side effects.

Having easy access to clean water. In sub-Saharan Africa for example, 300+ million people regularly risk disease and death just from trying to be hydrated
- Long time ago, I was a volunteer in Africa. The country where I was had experienced periodic droughts, and for a while I was able to get one bucket of water every two days, about 12 l. Cooking, drinking, washing, everything.
  It was a very unpleasant and enlightening experience.

Living past childhood.
Yes, lots of people feel their lives are awful, but compared to material living conditions even a few hundred years years ago nearly half of all children died before reaching adulthood, and the vast majority of the rest lived harder, more grueling lives than our own, with more illness and injury than us.
- Yep, and you only need to look at other countries to see how it could be. Children are really vulnerable and just die a lot, as awful as it is.

one I think about a lot: having abundant hot water (for cooking, showers, baths, cleaning, etc.)
and echoing what others have said, having abundant potable water.
I also haven't ever experienced a famine in my life - I have experienced more food security than most generations before me. (For me the worst case experiences were eating food that was thrown away, not eating weeds from the yard because my belly hasn't had any food in a week.)
- Yep, it's like when your hot water packs in, you realise how useful it is. Cold showers are unbearable. Washing up is a nightmare without hot water. It's something we really take for granted

Time. You can never guarantee that you have more of it because life is sometimes cruel.

A lot of recipes online take it for granted that you have access to a wide variety of ingredients and ethnic stores. I live in a small town with one small Hispanic grocery and ordering stuff online is expensive.
- Yep and spices amounts vary wildly depending on quality! Never mind how hot they are.