This is an intriguing question--and no doubt it hits on what makes Maugham's story so interesting. I would be strongly tempted to follow Wilson's example under the same circumstances. However, I would not be content to do nothing for twenty-five years. Maugham makes a great deal out of Wilson's love for the beauty of the setting in his story. No doubt the island of Capri and the Bay of Naples are beautiful places, but I personally would not be content merely to live anywhere and do virtually nothing but enjoy a beautiful setting for the best years of my life. If Maugham hadn't given his character Thomas Wilson such a passionate love for Capri the story wouldn't be convincing.
Maugham characterizes Wilson as a man with no particular interests or talents. He is not like the lawyer in Chekhov's story "The Bet" who spends fifteen years in solitary confinement but utilizes the time learning languages, studying philosophy, even teaching himself to play the piano, and making the best use of his unique situation. Maugham tells us that Wilson had a piano in his cottage.
He played some music by Beethoven. He did not play very well. But I saw that he enjoyed playing the piano.
Evidently Wilson had some interest in music, but not enough to study it seriously. He is without talent and without ambition. Oddly enough, with his appreciation of visual beauty he never took up painting.
He lived a quiet life. He bathed in the sea, he went for long walks, he played cards and he read books. He was happy to be by himself, but he also enjoyed meeting people from time to time.
The title of Maugham's story is derived from the episode in Homer's Odyssey in which the members of his crew become addicted to eating a type of narcotic lotus plant and lose all desire to do anything but sleep and dream like opium addicts. Maugham himself does not appear to approve of Wilson because his own character was so different. Maugham was a highly successful writer of plays, stories, novels, and nonfiction. If he had to spend twenty-five of his best years on the Isle of Capri he wouldn't have run out of money but would have enriched himself by utilizing his intellect and his talent.
I myself would have tried my best to do the same. I wouldn't have been content to watch my twenty-five-year annuity gradually dwindle away without making an attempt to do something to stretch my income. But I would have liked very much to have had twenty-five years of freedom to live my own life and do the kind of work I wanted during those priceless years between youth and old age.
"The Lotus Eater" is somewhat reminiscent of Somerset Maugham's novel The Moon and Sixpence, based on the life of the great Impressionist painter Paul Gauguin (1848-1903), who abandoned his family and his job as a stock broker to live on islands in the South Pacific where he could devote all his time to his painting. See the eNotes reference link below.