Creating video games is not hard at all. If anything, it needs dedication. Lots and lots of dedication.
Especially, using the UE4, it is very easy to create a computer game for many platforms, which looks quite good at the same time. You can use the latest tech and buy anything you cannot do yourself at the marketplace.
That being said, after 20h you should have a sandbox with a few basic shapes and a bit of logic to interact with the world. UE4 takes away all the hard stuff, and prototyping with Blueprints is very very easy.
Even though creating a simple sandbox is easy and prototyping very quick, you will need hundreds of hours to get a MVP. As soon as you have it, you still have to translate your Blueprints to performant C++ code. After that, it is adding features, fixing bugs and re-balancing stuff. Making a full game is still lots of work, even though it is quite easy. That's my hands-on experience with UE4. As I said, you need lots of dedication.
Don't forget that UE4 is just a tool. You need content (textures, Normal Maps, meshes, UV(W) Maps, Alpha Maps, materials, sounds,......) and knowledge (for example about game design, game programming patterns, C++, knowledge about engine internals, shading techniques, etc.). You can buy lots of assets, and you can gain a lot of knowledge as you go by hands-on experience. Just make sure you know that your first games will not necessarily be AAA quality. They will be your training games and you will get better with each game you complete.