64 GB of RAM is overkill for most people and the average user and most gaming.
16 GB of RAM is most often enough RAM for the average user, but 32 GB of RAM is ideal for gaming, video editing, multitasking etc.
Although if you do, do a lot of video editing or 3D rendering, running multiple virtual machines or do any specific high end simulations then 64GB would be needed and be a good idea to have that much RAM.
People that need 64 GB of RAM are video editors, graphic designers that use memory intensive applications like Adobe Photoshop, 3D artists, After Effects or Premiere Pro.
Or if you're a software developer who frequently uses multiple virtual machines for testing or development.
Or if you use some demanding simulations, like flight simulators, for example Microsoft Flight Simulator or if you use your computer for scientific research then you may require 64 GB of RAM or sometimes more.
Although the average user does not need 64 GB of RAM, such as for basic tasks like email, web browsing, watching YouTube, streaming, office applications etc.
And most gamers don't need 64 GB of RAM, although 32 GB of RAM is recommended for the latest AAA games, but 64 GB of RAM dose not provide any significant performance improvements for most gaming scenarios.
And if you only use your computer for tasks like light photo editing, casual gaming, streaming, light video editing, etc then 64 GB of RAM would be overkill.
Although it doesn't hurt to have more RAM than you think you'll need.
But for most people 16 GB to 32 GB of RAM is enough.