I have 1TB hdd

2TB external HD for my Wii U. Haven't needed to on anything else except I keep deleting stuff for new stuff on my 3DS.

I go physical so I didn't have to buy anything for my home console. Plus, Nintendo games are generally small so they don't take up too much space either..

I did buy an 8GB SD card for my 3DS though

No. I'm happy with the 500GB HD of the PS4. I only install games that I'm currently playing (between 2 and 4 games), so 500GB is fine for me.  

I upgraded my PS3 to a 500GB HDD.
Will upgrade my PS4 to a bigger drive when I need to.

When I get a Wii U I will buy a dedicated external drive.
I feel that upgrading to bigger storage, compared to what these systems originally come with is kind of a necessity nowadays with the large install sizes of modern games, unless you're fine to keep deleting stuff to make room for other games.

Had to buy extra memory for my Wii U and a bigger SD card for my 3ds but that's about it.

I bought a 800gb HD for my PS3 last year.
Thing is I am a physical box gamer, its just over many years the PS Store sales and classic games (and install data) got larger than 300gb.

More storage for my 3DS.

And will need to get something for my Wii U real soon (but I hear USBs are bad to use).

Nope. My 250GB PS3 has seen about 39 physical and 4 digital and I've only used about 90GB or so.

I just delete my stuff that I don't play anymore. No need to waste more money.

Nope, I usually just delete stuff.