What could've happened to the Malaysia Airlines Flight 370?

I came across some YouTube videos on this case from 2014 and it is still a confusing mystery to me. How can a flight with over 200 passengers just go missing off the radar? It's very chilling to think of what those passengers could have experienced. What are your theories on this case?

I've got it down to either aliens from space and/or other dimensions grabbed it in midflight, or it crashed in the middle of a very desolate patch of the ocean. Whichever sounds more logical.

So, obviously I'm going with my first theory.

MISSING Malaysian Airlines flight MH370 could have been brought down by a stowaway who was hiding somewhere on the Boeing 777, an aviation expert has claimed.

Others have previously suggested pilot Zaharie Amad Shah crashed the plane after taking it off course shortly after taking off from Kuala Lumpur in March 2014 with 239 people on board.(8/13/18)

It is a mystery to MOST on the planet.

How can it go missing off radar. EASY it goes out of range. The entire planet is not scanned by airport radar.
Satellites cover some parts of the planet.
The area the plane is suspected to be is HOURS of flight time or many days sailing time. The debris could be spread out over miles of water tens of thousands of feet down.
It took decades to find the Titanic and it was much larger and they knew within a few miles of where it should be.

It's very chilling to think of what those passengers could have experienced.
MOST probably did not know anything was amiss until the last few moments.

There's a documented case of a jet losing Air pressure the plane flew for hours. All on board basically passed out and passed away in their sleep. The plane eventually ran out of fuel and crashed.

Many things could have happened that lead eventually to a crash. NO ONE knows and all are just guessing.
The ocean is huge and not forgiving to a mistake. A simple bird strike could have crippled the plane.

A fire in the electronics is plausible. It happened to Swiss Air just after it departed New York it crashed near shore.
Over 3000 planes take off ever hour on the planet. About 100,000 per day 3,000,000 per month.
Most land as planned. There are about 3,000,000 or more parts on a large jet. It only takes one or two to fail in flight to end in disaster.

It is like the expression looking for a needle in a haystack and the haystack is somewhere in a million square miles.under 30,000 feet of water. The Indian Ocean is about 27,000,000 sq miles.

Who knows.

The number of people on board has no relevance to how a plane could go missing.

There's undeniable proof of pieces of wreckage from the plane washing ashore. The serial numbers match. It's just a matter of where it crashed. Clearly the captain was instrumental and knew what he was doing. My guess is look at the deepest section of ocean in the range