system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is Nvidia buying ARM? Why is ARM so important, and why aren't other companies interested?

Like the title, I've heard a lot about Nvidia's purchase of ARM. Why is ARM so important and what does it do? Why aren't other, larger companies trying to buy ARM?
gpt
ARM licenses the intellectual property for a line of small, low power microprocessor cores.  They are used in most cell phones and tablets today.  They are also starting to be used in server farms, because heat is a big deal in that application and their processing power/watt is good.    
  
A lot of companies wouldn't want ARM because they are incredibly expensive.  Some companies wouldn't want it because if they owned ARM then other ARM users would bail and look for other solutions, making it much less valuable.   
   
Nvidia has great processors for graphics and artificial intelligence, but no general purpose processor.  Until now.  They can't really get into the x86 market, but unless you want to play in the PC space that isn't necessary.  Having ARM gives them a full IP set for a lot of applications that are going to be big.  They will also not only get the licensing revenue from other people using ARM, but they can also fuck over potential competitors.