When Marc Blumencranz had an opportunity to compete in the 2013 Ironman Triathlon World Championships in Kailua-Kona, Hawaii, he spared no expense in his preparations to go the distance.

His outlays for the race — known simply as “Kona” among triathletes — went far beyond a wet suit and a new pair of handlebars for his racing bike. To help acclimate to the Hawaiian heat, he rented a house on Kailua-Kona’s fashionable Ali’i Drive, as well as a block of hotel rooms for the 10 days leading up to the race. He also hired a private chef to prepare his meals, then flew to Hawaii and housed not only his wife and daughter, but also his coach, massage therapist and physical therapist.

Total estimated cost: $100,000.

“My first reaction was, ‘You don’t need to do that,’” says Jose L. Lopez of Long Island Tri Coach, based in Mineola, who guided Mr. Blumencranz through the intensive, 10-week buildup to Kona. “I said, ‘I can still train you; I don’t need to be in Hawaii.’ He said, ‘I want you to be there with me.’”

Mr. Blumencranz, now 52, is a managing director for BWD, a large, privately held insurance brokerage and wealth-management firm in Plainview, N.Y. But his career success hardly makes him an anomaly in the sport. At events like Kona, it is not hard to find affluent competitors willing and able to put serious dollars behind their long-distance dreams.