3mbps=1.35gb per hour
100gb÷1.35gb=75hours

Eg, youtube vid,
1hour of 720p = 0.9gb
1hour of 1080p = 1.5gb
112hours of 720p = 100.8gb
67hours of 1080p = 100.5gb

1month = 720hours

So, with all the high tech gadgets today which you use daily and can easily multitasking like downloading updating and streaming, do you still think one cannot easily use beyond 100gb of data in a month?

Don't simply judge people for no life,  who knows if he/she got some serious illness that not capable going around so gadget and data is their only entertainment? Just think of a patient in hospital for example.