The question I've never gotten an answer for

[egyproductions]

Something thats always bothered me is aircraft carriers for military jets, they cost billions of dollars ands thats why not many countries own one. But why dont they just create water jets that can take off and land on water, like sea planes.

[Lethn]

http://www.aerospace-technology.com/features/featurejulys-top-stories-qatar-airways-18bn-deal-boeing-worlds-largest-amphibious-aircraft-4335288/

The basic problem is amphibious vehicles are complicated and difficult to make, so they come with a huge price tag, so it's much easier to build a massive aircraft carrier and just transport ordinary planes across the ocean rather than waste all that money on one plane.