Why is nihilism popular...
Well. First of all I want to say I don't think nihilism has any truth to it, but I think it has to do with why any idea is popular. Or "viral" is a better word, because ideas have to function on some sort of merit and they they do this aggressively and forcefully, they impinge their popularity in the same way gravity forces you to the ground-- the word 'viral' captures that aggression. This is how ideas function. Now...
Let's say we invent a new idea. Let's just call this idea 'random pounding on the keyboard' and give it the name: qlkjlkdnmf;lkasdfjk ;'a[ psdfksodfpoj qwef qefpjv /. That's the idea. It's not much of an idea, right? So you would be on pretty firm ground if you guessed that "qlkjlkdnmf;lkasdfjk ;'a[ psdfksodfpoj qwef qefpjv /" won't be trending on TikTok tomorrow, or in 10 years. It won't be the new slang kids use. It won't be on Urban Dictionary. And so on.
Why? Because it's not ... sticky. It's not viral. It doesn't have utility and power behind it. It doesn't do anything useful. Notice how we didn't say anything about its truth? Or how many tragedies it solves? That's because those things aren't actually the most important for how viral an idea is. There's a heirarchy to it. There's how good something is(ethically), there's how true something is(regardless how bad or good it is), but then there's how useful something is for survival(regardless how ethical or true it is), at the very very top of the heirarchy. Nothing beats this quality, for how viral something is.
Nihilism is useful for survival, so it's popular. But why is it useful-- doesn't it sound a little dark and depressing? It's useful, because our world is hellish. It's one where bad people win, and lots of innocent people get sacrificed in the process. That's how the system on our planet works(you can't fix this, because you'd have to beat the bad powerful people who rule things and to do that, you'd need to be like them). That is hellish and monsterous, and the more in touch you are with this aspect of our reality, the more difficult your life will be. Even if you don't understand that the world is this way, the fallout of the world being this way negatively touches everyone's life-- all conscious things suffer due to this feature of our world, not just humans.
But... what if you just didn't care? What if... it just didn't matter really that a child was being abused right this second? Right as you're reading? Or thousands of animals screamed in pain as they were eaten alive? As they've done for not just millions of years(notice how we can't quite wrap our heads around this number?), but hundreds of millions of years?
Hmm. Sure sounds terrible and hellish, if words like 'terrible' and 'hellish' are to mean anything.
Ah but... no matter. Because it's meaningless. Everything is meaningless.
Ahhhh. Much better. That's why it's popular.