And I'm amazed that you can use 50 tabs at once.

You can easily have two VMs and Chrome with a lot of tabs open together with some other apps with 16GB of RAM. The truth is, that only a fraction of all computer users need it. Many people are mistakenly thinking they need 32GB RAM. That is because the memory is already allocated for Photoshop, so OSX just needs to make that passive memory (it became passive when you closed Photoshop) active again. Now it will open almost instantly (1-3 seconds). First time after a cold boot it will take 10-15 seconds to load. It's only passive to be able to quickly activate that memory without having to allocate it again, when opening frequent apps. Passive memory is the same as free memory other applications can use that memory. So in the end of the day, when you'd have tons of apps running, 'free memory' might show a small number, but take a look at how much the passive memory uses. If you have 16GB RAM, and have 3GB active, and 10GB passive, activity monitor would only say you have 3GB free memory, even though you have a total of 13GB to take from. if you open a VM that uses 4GB, and then close it, that memory will still be allocated, but as passive memory (so that other applications can 'eat' that space). Many people make a mistake not taking passive memory into the consideration.

Ram memory for macbook pro mid 2012