There used to be a saying on the PGA Tour that you didn’t win for your first five years. It just would have been disrespectful.

Well, that sentiment has been dead for a while, and the new generation has buried it forever.

Led by two California kids who grew up playing high school golf against one another — Matt Wolff and Collin Morikawa — the newest class of pros is entirely unafraid of what lies in front of it. Since leaving their respective colleges this spring, both have come on Tour with sponsor’s exemptions, and both have taken that opportunity to win at the highest level.

It not only secured their playing privileges going forward, avoiding the minor league tour or qualifying school, but it cemented them as new-age players with progressive and aggressive mindsets.

“I think when guys come out of college, they think they just want to beat everyone in their class. And if you beat them, that means you’re one step ahead. We want to beat everyone,” Morikawa said in a quiet moment with a few reporters on a stormy Wednesday at Liberty National Golf Club in Jersey City on the eve of the first round of the Northern Trust, the first leg of the FedEx Cup playoffs.

“I think that was the belief system we all had,” the 22-year-old continued. “I can’t speak for [everyone], but I know we all have that inner confidence in ourselves that we can do it. I think that’s what separated us.”

What separated Wolff has always been his unconventional swing, a herky-jerky motion that produces prodigious drives and terrific iron play. The 20-year-old won in his third tournament as a professional, making eagle on the final hole of the 3M Open in Minnesota in early July to finish the four days at 21 under — just one shot in front of Morikawa and Bryson DeChambeau.

“It’s been pretty awesome,” Wolff told The Post on the driving range Wednesday before his pro-am round was canceled by strong thunderstorms. “It’s a dream come true, being on the PGA Tour, winning out here and getting my Tour card. And to have it be done with Collin, who I grew up playing high school golf with — it’s pretty cool to see us go each step of golf. It’s a cool journey.”

Morikawa went to La Canada High School in Flintridge, Calif., while the younger Wolff went to Westlake in Thousand Oaks. Wolff’s team was a powerhouse that featured five NCAA Division I golfers, and they organized to play Morikawa’s team for better competition.

Morikawa then went on to college at Cal, where he spent four years before turning pro. His first tournament was the RBC Canadian Open in early June.

“When I stood on the first tee, the first tee shot, at RBC, my first professional event, I felt as comfortable as ever. I felt like I belonged there,” Morikawa said. “There were expectations, but it was more just goals for myself. I sat down with Justin Thomas at RBC, what he told me [was], ‘If you’re good enough, you’re going to get out here.’ People have different timetables.”

It took Morikawa all of six events before he won, at the Barracuda Championship two weeks ago in Reno, Nev., the event held opposite the British Open. That put him and Wolff in the same category as gatecrashers to one of the most exclusive clubs in golf.

“Obviously, I didn’t expect to win out here this quickly, but I knew I could,” Wolff said. “It happened really quickly, but I felt like I was ready when I turned pro to be able to come out here and win. That’s what I did. These guys are really good, but I feel like I can compete out here.”

Whereas those who came before them might have been too reverential to the previous generation, these two young men remain respectful but unafraid of beating anyone.

“We don’t know what’s going to happen, but we did win very early, so there are going to be things and expectations [the media] puts on us,” Morikawa said. “But we’re not trying to just beat [the preceding generation]. We’re trying to beat everyone. I think that’s what different.”