But despite devastating lows that drove him away from the sport for the better part of a year and admitted uncertainty over whether he'll ever return to his best, the 27-year-old American once touted as the heir to Michael Phelps is ready to test himself again at the Paris Olympics.
"I don't know what's possible," Dressel said after a rollercoaster US trials, where he won the 50m free and 100m butterfly to earn a chance to defend two of his three individual titles from the pandemic-delayed Tokyo Games.
He missed out in the 100m free -- finishing third behind up-and-comers Chris Guiliano and Jack Alexy in a blistering final that put Dressel in the mix for a relay berth.
It's a far cry from his build-up to Tokyo, when he went into the Games as the two-time reigning world champion in all three of his individual events and emerged with five golds to cement an Olympic legacy that began when he earned two relay golds in Rio de Janeiro in 2016.
But Dressel's pursuit of perfection came at a price, and he stepped away abruptly at the 2022 World Championships, later speaking candidly of feeling mentally "broken" by the demands he put on himself.
"I would love if I could get back to the point where I was five years old," Dressel said. "It was simply swimming, that's all it was. You were just swimming, there wasn't any media, you didn't care how you felt ... that's what drew me into the sport and there's things that I've put up with that I don't like or things about the sport that I hate."
That included comparisons to Phelps, who earned 23 gold medals over five Olympic campaigns and established himself as the standard bearer for the sport not just in the United States but globally.
Dressel remains in awe of Phelps's longevity and excellence and says now the comparisons seem unfair.
"I get it, trying to find the next guy," Dressel said. "But I have said multiple times I'm not Michael, at all, and I'm fine with admitting that.
"I think I'm pretty damn good at what I do. And I've exceeded a lot of my expectations in the sport, and I have drained the talent that I have, and I'm still continuing to do that."
But Dressel admits he isn't sure how much more there is to mine.
"I don't know if I'll ever go a best time ever again, and that's tough to say out loud, it really is," Dressel said.
"When you're 19, 20, 21, you keep chipping away, chipping away, chipping away. I'm still working harder than ever, finding outlets, finding every path I can take to shave those couple tenths.
"I'm really good at racing. You put me in a race, I will make it close, as close as I possibly can, even if I have to try to kill myself to get there."
Family man
The coach helping Dressel find out just what he has left is Anthony Nesty, who won the 100m butterfly at the 1988 Olympics for Suriname and now coaches in Florida.
Dressel is also buoyed by the support of his wife Meghan. The couple welcomed the birth of their first child, son August, in February.
"Meghan knows what goes into this, not just the parenting side of things but she gets to see firsthand the struggles that come with the sport," Dressel said. "The tears that come with it, the frustration and then also the high points, and getting to share that with them, because they go through that as well."
Dressel also felt the support of fans that made his third Olympic trials a "totally different experience" to "bombing" as a youngster at his first trials, making the team in a "nerve-wracking" 2016 and then seeing his face plastered everywhere before Tokyo.
"The crowd, feeling the love from everybody, that's something new," he said.
