“Doing that cost me a shot,” the Ryder Cup left-hander told the Golf Channel. “My attitude cost me this golf tournament and I can’t be allowing that.
“You got to be in the right position at the right time to allow a round like today to finish off.
“Big, big reminder for me that attitude has got to be right for 72 holes, not just 36.”
MacIntyre made five birdies in racing to the turn in 30 in Honalulu and picked up further shots at the 15th and 18th to reach 12 under par for the week after a bogey-free final round.
“Felt like I missed in the right spots off the tee to give myself chances and I putted beautifully,” the US Open runner-up said.
“Massive reminder of attitude has to be spot on. Last year, I felt like I done a great job of that.”
Gotterup, meanwhile, made a closing 64 to finish two ahead of Ryan Gerard, with a third American, Patrick Rodgers, one further back.
England’s Harry Hall claimed a share of sixth place after carding a 69.
