Smith moved his uncle into his USA home following the Australian bushfires.
Brendan Steele chips onto the 10th green during a playoff against Cameron Smith during the final round of the Sony Open PGA Tour golf event, Sunday, Jan. 12, 2020, at Waialae Country Club in Honolulu.
The play-off saw Steele hit a wedge over the green from the middle of the fairway and fail to get up and down to save par, allowing Smith to secure victory with a two-putt par from 10 feet.
"I just hung in there, and what do you know?" "Nobody played golf as it seemed", said Smith.
"Things just collapsed. Sometimes you need a bit of luck to stand up and you never know what can happen".
He two-putted for par at the 10th hole as Steele battled to a bogey to fall short in the play-off.
The extra holes began on the 10th hole in the wet conditions and fading light with Smith holding his nerve with a two-putt par from 10 feet to add to his lone previous PGA Tour title - the 2017 two-man team's Zurich Classic in New Orleans.
"My first individual win on the PGA Tour, it's definitely going to be one I never forget", Smith said.
"I've been out here four or five years now".
McDowell entered the final day well off the pace but stormed into contention with four pars and five birdies on the front nine.
Smith is among the Aussie golfers at the event donating a portion of their prize money to the relief effort for the blazes Down Under.
"I mean, just had to hang in there", Smith said of his win.
For Steele, who led alone from the first tee until the penultimate putt of the day, it was a gut-wrenching defeat.
"Everything that could go wrong went wrong today", said Steele. "Kind of everything that could have gone wrong went wrong today. I'm just a California kid who doesn't like rain so, I was just trying to grind and I worked as hard as I could and it just wasn't good enough".
Smith closed the gap with a five-foot birdie at the next and moved within one when Steele three-putted the 13th from 40 feet, only for the Australian to drop a shot of his own at the 15th after failing to get up and down from a bunker.
On the 422-yard par-4 third, Palmer had a bogey after hitting the green in 4 and one putting, moving Palmer to 1 over for the round.
A two-time Australian PGA champion, Smith's career PGA Tour earnings have jumped to $10,645,748 ($A15.4m).
The Queenslander made birdie on the par-5 18th hole in regulation to join final-round playing partner and overnight leader Brendan Todd at 11-under 269. Maintenance crew kept having to squeegee the soaked 18th green.
But Steele endured another 15-minute wait over the lost ball, then sprayed his second shot over spectator tents and way left of the green.
With his bogey on the 18th, Palmer had to settle for a 68 and tied for fourth with Graeme McDowell, who had a 64 to match the low score Sunday, and Kevin Kisner, who played in the final group but made only one birdie on the back for a 69.