upgrading laptops. Possible or not?

I've done my research and have found out that laptops can only have thier hard drive, andRAM upgraded, andthe CPU and video card can't be. If that's true, why is that?

It depends. Some laptops are made so you can upgrade components like the video card but most are integrated so you would have to buy a new motherboard.

You can also build your own laptop from scratch. They have kits for it. The other concern if you do upgrade is heat. But yes if you get the right laptop you can upgrade the video card. Not sure about cpu but likely possible if the motherboard supports a faster cpu