Venture capitalists who have bid against Andreessen Horowitz say the firm often comes in 50 to 100 percent higher than many other bidders, as when it led an ill-advised $40 million investment round in a daily deal site called Fab in 2011, which valued the company at $200 million. (The firm has occasionally passed on big deals, like one with Uber, that it felt were too costly.) These prices are flattering to the entrepreneur, who suddenly runs a company worth twice as much on paper as previously thought.

It is an article of faith in Hollywood that hiring stars significantly increases the chances of scoring a blockbuster. Alas, this is not the case. Studying movies released between the mid-1980s and mid-1990s, Arthur S. De Vany, an expert on film economics, found that the participation of only 19 star actors and directors appeared to improve a movie’s chances of grossing more than $50 million. And the stars’ stunning paydays often leeched away studio profits.

The forces that govern movies and start-ups are remarkably similar. They both follow what is known as a power-law distribution, meaning that the overwhelming majority of investments lose money, while a small fraction break even or become marginally profitable, and an even smaller fraction become wildly successful.

Mr. Andreessen and his partners seem to believe they’re playing a role analogous to that of Mr. Ovitz and his fellow superagents: They do what it takes to lock up talent, which they eventually sell to someone else at a huge markup. This generates profits for themselves and a nice payday for the stars, whether they are Hollywood celebrities or entrepreneurs.

But what if the Andreessen Horowitz partners have the analogy wrong? Rather than profiting like Mr. Ovitz and his fellow agents, the venture capitalists may be more like the Hollywood studios — chronically overpaying for projects whose costs they can rarely recoup. Mr. Andreessen and his partners have invested so much in so many start-ups that it would take a remarkable string of successes to make the approach pay off. For all their skill — the firm bought into the likes of Airbnb, Instagram and Pinterest relatively early — their track record suggests it’s unlikely. Already, they’ve suffered a few impressive flameouts, including Fab, on which they are likely to lose tens of millions of dollars.

Even when they pick well, they often bid so much for stars that the return is relatively modest. It’s easier to triple or quadruple your money when you’ve invested $10 million in a $100 million company than when you’ve invested nearly $100 million in a $1 billion company, as they did with the daily deal site Zulily. There are only so many companies that are acquired for billions of dollars or reach that kind of price through an initial public offering. Fewer retain such valuations — Zulily’s stock price has fallen sharply since last year.

More than is the case with other firms, the fate of Andreessen Horowitz may be closely tied to that of the overall tech market. If prices remain buoyant, the eye-popping valuations of the firm’s top-performing companies will keep it profitable and losses will be containable. But if the market turns, Andreessen Horowitz could have serious trouble.