salaries are opex, data centers are capex, you can't compare them in the same timeframe.

4B over 5 years is 20B, which is significant.

4B over 5 years is still 4B. It's 0.8B/yr

If I read it right, the 4B ballpark figure is based on total annual per employee cost of 500k * 8000 employees, so the figure is actually 4B/year. 20B over five years.