Being a scientist is like having one's own business

• Product is knowledge; solution to problem; "truth".
• Consumer is other scientists, engineers. (Eventually, when knowledge is applied, it is also consumed by government, industry, and buying public.)
• Capital is research grants from government, university, industry.
• Revenue is recognition/citations, salary.
• Employees are technicians, students (although it's debatable to what extent students are employees as opposed to trainees). The scientist must manage these personnel.
• Marketing the product in "the marketplace of ideas":
  • publish in peer-reviewed journals
  • give presentations at conferences
  • maintain service on past products
  • convince people that what you've done is interesting and true
• Competition for "buyers" and investors is severe.
  • Extremely limited funding pool from federal, state, university and industrial agencies.
  • The product must be of rigorously high quality and quantity to get capital or revenue.
• Work hours are as long as it takes to generate the quality and quantity of product to compete in the marketplace of ideas. A scientist's work hours are flexible, but extend to any time of day and night, year 'round.

But, the goals of science differ from the goals of business

• Science is wonder combined with skepticism (see Carl Sagan's book, "The Demon Haunted world"). "Wonder" is the urge to discover and explain, "skepticism" is the rejection of proposed explanations without strong evidence.
  (Aside: Statistical methods are a spectacular expression of the culture of skepticism and free competition in the marketplace of ideas.)
• Goal is to discover the truth (or as close to the truth as possible).
• Goal is not only the "bottom line" of revenue and capital.
• Therefore the market model of science only goes so far.

The role of tenure

• Sometimes the reasonably-pursued truth is not very marketable: it might be merely unfashionable or overtly politically incorrect.
• To protect the reasonably-pursued truth, there is tenure. Tenure is a form of job guarantee. But it is not a salary guarantee! A scientist with tenure can't be fired merely for being unpopular or unmarketable. But salary is still subject to merit review, which is largely based on market forces.
• (As asides, note that U.S. Supreme Court justices have tenure for similar reasons. Also, when dictators rise to power, the scientists and other intellectuals are among the first to be disposed of.)