QFT.Compared with the cost of providing a set of users with laptop computers and a domain to log on to, the costs are reasonable. A company with a network of chromeos devices could probably make do with a smaller IT dept than one without, making substantial savings. Fewer servers, less maintenance work, less downtime.. it all adds up.
The hardware cost isn't the biggest factor in these sums, and if you think it is you're missing the point.
Most costs an IT department has is Body's not gear. You get the write off hardware over a 3 year period for a business expense..You have to pay taxes for every person on payroll.
Think of it like this: average Business Dell (office, dock, monitor, keyboard and mouse) runs you $1300 which you keep for 3 years. 1300/3 = 433.34 per year. Low Level IT Support desk starts at 30,000. 30,000/433.34 = 69 laptops per one person salary. That doesn't include payroll tax or insurance.
Most sites have 1-2 techs and one manager per 3-5 sites. Managers make 60-80k. If your big enough you have domain guys and network guys that your paying too...they are much larger salaries...100k+ easy. See how quick bodies add up.