There's nothing to get confuse in there. If you can afford 2TB just go and buy maybe later you will have the files to save.
what files do a 15 year old will store in 2tb storage? goat porns or turtle porns? or mixed? yeah this sounds inappropriate but still,when I was 15 year old, I had only 320gb storage, from which, half of it used to stay free, now I got 640gb(320 +320gb 2 HDDs) and a passport external HDD of 1 tb,they're still less