system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did LED lights become so cheap to produce?

Through the 90s you never saw LEDs, and their lifespan was awful.  Now, they are so ubiquitous you see them embedded in every cheap thing you can imagine -- and super bright ones, at that.

I have an LED police flashlight that could blind Zeus.

So, what advances were made that allowed them to be produced so cheaply, and so efficiently?
gpt
I don't think that an extended lifespan is the main reason why they are so popular nowadays, but it's rather the color:

LEDs have been invented in the 1960s, but the colors which could be produced in a cheap and efficient way were red, yellow and to some extend, green. However, in the early 1990s, a Japanese physicist, Shuji Nakamura, found a way to produce LEDs which emit blue light.

Using red, blue and green LEDs together, you can mix these and get white light (light of any color, actually). It took some time for these to come from the lab to the consumer (probably also advancing in lifespan and brightness).

Essentially, without blue LEDs we wouldn't be able to use LEDs to light a room or as a flash light.