Thomas was at first downbeat as he had failed to win the season-ending Tour Championship, losing the tournament which was held on the outskirts of Atlanta by a stroke to 23-year-old Californian rookie Xander Schauffele.
The 24-year-old Thomas told reporters that finishing runner up but ending the year as the FedEx champion "feels very weird."
Victory for Thomas at East Lake would have secured him a sixth tournament win of the year, a feat last achieved by 14-time major winner Tiger Woods, but the Kentucky native fell short as his compatriot Schauffele carded a two-under 68 to finish 12 under par, securing a second PGA Tour victory.
"At first I'm sure people were kind of shocked at my reactions or my tone because I was ... I mean, I wasn't mad but my competitive nature, I mean I was upset. I felt like I had a great chance to win this tournament and I didn't," Thomas said at a news conference.
"I wanted to win six times this year. Coming into this week and I knew that just from looking at social media I think I would have been the only person other than Tiger to do it in the last however many years, and anytime you're in the same sentence or record books with Tiger, it's pretty impressive.
"So I wanted to win for that and I knew if I won this week I would win the FedExCup.
"It's odd getting something so tremendous, one of my best achievements in my career without winning a golf
tournament, so it feels different but it's still great."
Thomas can reflect on an incredible year which has seen him win five tournaments, one of which was the US PGA, in only his third year on the tour.
He told CNN that 2017 had been a "life-changing year."
"It's been an unbelievable year, a special year. To cap it up with the FedEx trophy and, the title, it's a great icing on the cake," he said.
"I feel like I'm only getting started in terms of accomplishments. I just need to keep working hard, I need to keep having good goals and keep my mind straight and see what I can do in this game."
Seeking advice from Woods & Spieth
Coming into the Tour Championship a number of players had a chance of winning the $10m payout.
Jordan Spieth, a three-time major winner, began the tournament with a 200-point lead over Thomas and was projected to win the FedEx Cup after an eagle on the 10th and a birdie on the 13th. But a bogey on the 15th ruined Spieth's chances.
Thomas charged up the field -- birdies on the 16th and 17th saw him move into a share of the lead, but Schauffele birdied the last to secure victory and $3.5 million in prize money.
Thomas admitted he laughed when he realized that close friend Spieth, whom he has competed against since they were both 13 years old, was in contention for the FedEx Cup.
"I thought honestly, this probably will happen and the golf world will completely blow up and lose its mind if Jordan and I were in a playoff for the FedExCup," he told reporters.
"I don't think anybody would have known what to do with themselves."
The FedEx champion said he would turn to Spieth and Woods over the course of the next few weeks and seek their counsel on coping with success.
"I'm going to try to spend a lot of time with Tiger and then definitely call and talk to Jordan because they're the two people I'm closest to that have done something close to this and they've both achieved way more than this," he said.
"I need to understand how to reevaluate my goals, how to reset my goals, how to deal with everything. I mean, I'm going to have a lot more obligations, I'm going to have a lot more people wanting my time.
"I'm going to have a lot higher expectations from you guys, from the fans, from everything. So I'm going to need to understand and get better at handling all of it.
"I'm going to rely on guys like them and other guys a lot just to help me out to get a good idea and game plan. And then, you know, after the Presidents Cup I get a couple days off and reset the goals," added Thomas referring to the tournament between a US and international team that tees off later this week.
As for the extra $10 million in the bank account, Thomas said he did not play for the money.
"It's like I'm going to be fine financially for my life," he said.
"I plan on winning a lot of golf tournaments in my career, and if you play out here for the money, I don't think you play for the right reasons.
"I've never wanted to do anything in my career for that reason. It's a tremendous bonus. I guess a nice cushion you could say.
"It's fun to have because yeah, obviously, who doesn't like it, but I work hard and I put all this preparation in and I'm competitive because I like winning and I like trophies and I like being in the history books and I like having my name on trophies that not many people's are on.
"It's not the money. The money is just a nice bonus that comes with it."