For most software companies, the overwhelmingly highest expense is going to be employee salaries and direct costs of employment. At many companies that is 80% of all expenses. (Exceptions: companies with large advertising costs, and platform companies with exceptionally large costs that scale with the success of the core business, like you might imagine Twilio, Heroku, or Stripe having.)

Consider a 3 man company which raises $5 million in investment and expands to 10. They'll chew through a million every six months just in payroll costs.

Ten is a fairly small company. There are many VC-backed companies which are in the 100~200 employees range. Payroll scales pretty much linearly, so...