honestly the best way the world can end and the way i think it will end is kind of like the show revolution, where an organization controls trillions of microscopic nano bots that control everything, like power, elements, death, healing etc..., So if this power gets in the wrong hands OR it malfunctions, it could destroy the entire planet or light the air on fire. this is how i think the world will end.

The world will end when there are no humans left. Think about it... Quantum Physics tells us that life if literally made of consciousness and that everything we see is just a hologram. E.G. life is only there if we see it. Therefore, if we are not there to witness life, does it still exist? Think about it

I think we will all kill each other cause ya know, people suck.

Just for the sake of mixing things up, not that I actually think this would happen.
A type of apocalypse that nobody really considers is worldwide infertility.
This is portrayed well in the film 'Children of Men', every woman becomes unable to have children.
the film jumps in when the youngest person in the world is 18 years old, society has broken down except in Britain where refugees are kept in cages and sent to deportation camps.
Quite a grim view of the future, but anything can happen.

Personally, I think Human civilization will fall at the hands of Humans, the world itself will be destroyed in around 5 billion years unless there is a cataclysmic asteroid impact that shatters the Earth into tiny pieces.

I think the "Lucifer Experiment" will be the death of us. This basically means there becomes too much hate and greed in the world and we all blow each other up