And still making an easy profit.

Calculating it through, I think they make about $5 profit per terabyte per year, and that's using normal prices that I'd pay for hardware and power as a consumer in America.* That is considering costs for: buying drives (with a mean time to failure of 2 years), buying a server, power for the server and drives, and storing the data with 3x redundancy (two drives can fail and a third and fourth still have it).

* "In America" must be noted because power is dirt cheap there. Like .09 dollar per kWh while here we pay .2 euros.

I'm thinking of starting an online backup service myself for a fair price and no corporate bullshit, but as a student with no money nor experience I'm very hesitant. But I might try!