LOS ANGELES — Before Mac DeMarco bought a lovely blue home with a pool on a quiet hill here in Silver Lake — the first real adult spoils of a surprising career built on seeming like an affable deadbeat — he gave out his exact address to fans, not exactly expecting them to show up in droves.

“Stop on by — I’ll make you a cup of coffee,” Mr. DeMarco, a mischievous singer and songwriter, said on a whim at the end of “My House by the Water,” an instrumental track from 2015. His place, a four-bedroom on the beach in Far Rockaway, Queens, was relatively secluded, directly across Jamaica Bay from Kennedy International Airport. But accessibility aside, people soon started showing up, and they didn’t really stop for the next six months.

“We had thousands of kids, all through the day, all hours,” Mr. DeMarco recalled recently as he chain-smoked Marlboro Reds in his new backyard, surrounded by overflowing ashtrays and discarded cans of beer and seltzer. “It was crazy. I really liked it.”

True to his word and reputation, he played amiable host to those making the Rockaway pilgrimage — his longtime girlfriend, Kiera McNally, “was a good sport for as long as she could be” — even as summer bloomed and space got tight. “Sometimes we’d have like 40 people sitting against the sea wall watching us rehearse,” Mr. DeMarco said, insisting that the impetuous stunt did not lead to any negative experiences and only brought him closer to his fan base.