Simbine led a surprise South African double with teammate Henricho Bruintjies taking silver to consign Jamaica's red-hot favourite Yohan Blake to bronze on Monday night.
"I believed in myself, that I could get the gold medal," Simbine told the BBC.
"The 100m is an event of who's got the biggest ego and who can handle the ego the best.
"I didn't focus on what they were all talking about. I just focused on myself."
He stormed home at Carrara Stadium to win in 10.03 seconds while Blake couldn't overcome a stumble at the start and clocked 10.19.
"I lost from the start," Blake said.
Michelle-Lee Ahye became the first woman from Trinidad and Tobago to win a Commonwealth Games athletics gold when she won the 100m in 11.14 ahead of Jamaicans Christania Williams and Gayon Evans.
On a big night for South Africa, Chad le Clos became the first swimmer to claim the butterfly treble at a Commonwealth Games, winning the 100m on Monday to add to the 200m and 50m golds he won earlier at the Games.
The big names and blue riband events may have dominated Monday on the Gold Coast, but it was also an historic day for Pacific power at the weightlifting.
Teenager Eileen Cikamatana became the first Fijian woman to win a Commonwealth Games gold medal as the island nations dominated.
Cikamatana won the women's 90kg competition on Monday, while Samoan pair Feagaiga Stowers and Sanele Mao also claimed weightlifting gold for the Pacific.
The 18-year-old Cikamatana wept openly as the Fijian anthem played at a Commonwealth Games for only the fourth time - the first since 2002.
"I feel like I am on top of the world," she said.
"This is not the end, just the start."
Samoa had also only won three Commonwealth gold medals before Mao picked up their first for these Games with a total lift of 360kg to beat Indian favourite Pardeep Singh in the men's 105kg class.
"I fought for me, for my country, and for my gold medal," Mao said.
Stowers, also 18, came to the Gold Coast only hoping for silver behind controversial New Zealand transgender lifter Laurel Hubbard in the women's over 90kg.
But Hubbard damaged ligaments in her elbow when attempting a Commonwealth record in the snatch, leaving the competition open for the Samoan teenager whose coaches had been critical of the New Zealander's inclusion.
"I don't want to say this but it's unfair for her to compete," Samoan official Mary Opeloge said.
The Cook Islands continued Monday's Pacific flavour when they won their first ever Games medal with bronze in lawn bowls men's pairs.