A big bottle of wine sat in his basement for decades. It could go for $80K.

Mark Paulson bought a high-end bottle of wine for $250 in the late 1970s, and for the better part of a half-century, some of the finest, most prized wine in the world sat largely forgotten inside a cardboard box in his basement.

Since then, Paulson, a 72-year-old retired commercial painter, and his wife have had four children. Those children have grown up and had kids of their own. The area around their home in south San Francisco transformed from a cultural hub in the throes of hippie culture into a tech-obsessed megalopolis of more than 7.5 million people.

Still, the bottle remained intact and undrunk in Paulson’s basement.

That’s changing. Later this month, Paulson will sell his bottle of 1971 Domaine de la Romanée-Conti La Tâche at auction. Bonhams Skinner, the auction house overseeing the sale, estimates that the jeroboam - a 3-liter bottle of wine also known as a double magnum - will go for between $50,000 and $80,000, as first reported by the San Francisco Chronicle. The large price tag comes in no small part from the fact that Domaine de la Romanée Conti in the French region of Burgundy is “unequivocally one of, if not the greatest winery in the world” that many experts believe makes the “purest expression of pinot noir,” said Louis Krieger, Bonhams Skinner’s deputy director of fine wines.

Scarcity also drives up the price. Output varies, but the winery usually puts out about 1,300 cases of La Tâche each year, Krieger told the Washington Post.

Paulson’s spectacular investment reveals how the wine industry has changed in the United States over the past 50 years, Krieger said. In the late 1970s, Americans didn’t drink wine, opting instead for liquor and beer. That started to change in the 1980s and interest has grown ever since. Then, in the 2000s, a growing middle class in China also started taking an interest. More than 40 years of increasing demand created a speculative market, in which investors buy bottles of high-end wine not to drink but to turn a profit.

Paulson was ahead of the average American’s sensibilities, at least when it came to wine. Born and raised in the canal zone in Panama, Paulson moved to San Francisco in 1971 after serving in Vietnam with the Navy.

One day in the early ‘70s, while sitting in Golden Gate Park with a friend, he spotted some of his sister’s childhood pals. They reconnected and became roommates, leading Paulson to fall in with a group of artists and musicians. His new friends, including members of the band called the Flamin’ Groovies, joined a wine-tasting group organized by Roger Brandt, a retired policeman who’d inherited a liquor store from his father.

Brandt got the group some of the best wines in the world at cost and taught Paulson and company about them - ‘59 Latour, ‘61 Cos d’Estournel, ‘67 Suduiraut. During one tasting, they drank their way through a half-dozen Romanée-Conti vintages dating from 1961 to 1971.

“The wines were so delicious, things we’d never had before,” Paulson said, adding that “there was an incredible amount of old wines around in those days. It was just amazing how many he had, and the prices were all reasonable.”

One day, Brandt told Paulson he was ordering some special wines and “kind of insisted” that Paulson shell out the $250 needed to get the jeroboam of La Tâche because it was a “once-in-a-lifetime thing.”

“I didn’t even hesitate, because Roger had become a really good friend,” he said.

Paulson ran with his wine-tasting crowd for years, building up his own collection: about 10 cases of rare and high-end wines, including the La Tâche. But in 1977, he got married, and three years later, they had their first child, followed by three more over the next eight years. Wine faded from Paulson’s life.

“I really stopped buying wines because as a painter, it wasn’t enough money to drink high-end wines and raise four kids,” he said.

Over the next few decades, Paulson drank his way through nearly all of the 10 cases he’d collected. But the La Tâche remained, perhaps because of its size, Paulson said. He never seemed to find the right occasion for a jeroboam, which contains the equivalent of four regular bottles of wine. He thought he might save it for his daughter’s wedding. Since she was born in 1984, that meant holding on to it for a while.

“It’s just been sitting downstairs in my basement for all these years,” he said. “Never really thought that much about it.”

That is until last year, when his son, who works at a paint store in San Francisco, brought up the La Tâche while talking to a customer in December. The customer, who has a collection of 5,000 bottles, said he might be interested in buying it. But when he came by the house to inspect it, he offered $5,000, which Paulson said he knew was way too low.

Paulson and his son told the contractor they had to think about it. His son hopped online to research its value and stumbled across an article in “the drinks business” about Bonhams Skinner selling a 1971 La Tâche jeroboam in October for $81,250.

“We were shocked. We were just, you know, flabbergasted, couldn’t say anything. We just kind of hugged each other and smiled a lot,” he said.

His son said, “Oh my God, Dad, you almost sold this thing for $5,000.”

Paulson’s son contacted Krieger that night, which led to Bonhams Skinner’s upcoming auction, which will also include five other bottles from Paulson’s basement that have vintage dates ranging from 1795 to 1870 and are expected to sell for between $1,000 and $4,000 each.

Paulson’s hoping the La Tâche goes for more than $100,000. Regardless, he plans to hook up his son with a commission of at least $10,000 and spend some of the rest on house repairs, and maybe a vacation.

After the auction, Paulson will still have four bottles that Bonhams Skinner didn’t take. He plans to drink at least one, pouring himself a glass when he “hears the big numbers.” He’s thinking he’ll uncork his ‘59 Latour, which goes for more than $2,000 a bottle.

But truth be told, Paulson isn’t much of a wine drinker these days. The income of a commercial painter didn’t allow him to keep pace with the skyrocketing cost of fine wines, and his early exposure to them ruined more affordable prosaic options.

Now, Paulson’s more of a beer guy. One of his favorites: Lagunitas Brewing Company’s Super Cluster IPA, and after the auction, he should have no problem springing for a few. Total Wine is selling six-packs in his area for $9.49.