“The Phantom of the Opera” will make show business history on Saturday with the 10,000th Broadway performance of an $8 million production that became an $845 million hit. But it is also something much more. It is the musical that has come to define modern Broadway by proving the purchasing power of women and tourists, the durability of repeat business and the lure of spectacle: ingredients for success embraced by producers of “The Lion King,” “Wicked,” “Mamma Mia!” and other smashes.

While “Phantom” has prospered from unparalleled word of mouth, a show as much for sightseers as for theatergoers, its unprecedented Broadway run has hardly been a foregone conclusion. When it opened on Jan. 26, 1988, big hits were few, and roughly half of Broadway’s theaters were empty. Yet thanks to persistent marketing, strict quality control and flexibility in ticket pricing (the worst seats can now be had for only $26.50), “Phantom” survived — in fact thrived — when shows with bigger stars and better reviews brought down their curtains.

The show’s 2011 box office performance was its most lucrative, and in December “Phantom” earned more in a single week, $1,579,428, than in any of the 1,256 weeks since the musical reached New York.

It’s a windfall for investors like James B. Freydberg, who recalled recently that he and his business partner decided to put $500,000 into “Phantom” in 1987 because they figured they might do better than in the stock market, which had just crashed on Black Monday. They have gone on to earn about $12 million from “Phantom” through Broadway and national tours, and still receive regular checks of $100,000 from a show that Mr. Freydberg hasn’t seen since opening night 24 years ago.