If the file you are showing us is really huge, you will not be able to read it right away via the json
module like so:
with open('users.txt') as f:
users = json.load(f)
Your impression of huge, however, may be different from the impression your computer has, so give it a try even if it's a few thousands of users in your file.
Now for the huge case. Here one big read will not be possible and you have to process the data line by line. Parsing JSON yourself is not a good idea, but when you rely on certain patterns that your input data show, you can write a simple iteration that will process each user block individually:
import json