The three-time world champion attacked on the Poggio climb last year and rode much of the 3.1-kilometre descent and flat into town at the front, but was narrowly beaten in a three-up sprint.
Kwiatkowski won ahead of Sagan and Frenchman Julian Alaphilippe (Quick-Step Floors).
"Yeah," Sagan said when asked if he was to generous in last year's finale. "But that's also the thing, the way you win. If you analyse how Kwiatko won last year... If I win like that, I'm not happy with my performance. Or we are playing fair or after, it's very easy."
Sagan indicated he would do the same thing again, preferring to "make a show" while winning the first Monument of the 2018 season.
"Well, everyone is different. We have difference personalities, that's life. That's why life is beautiful, everybody is different," he said of Kwiatkowski.
"I prefer to make some show for people and how it's going, it's going. It doesn't matter if you win or lose."
Sagan put on a show on stage six of the Tirreno-Adriatico, chasing back after he had narrowly avoided the crash with Fernando Gaviria (Quick-Step Floors).
He bunny-hopped a roundabout and weaved his way through the remaining riders to finish second behind Marcel Kittel (Katusha-Alpecin).
Critics often point out that though Sagan is the strongest, he wastes energy with his riding and tactics. He finished the Tirreno-Adriatico stage race in central Italy with three second places to his name.
The Slovakian has already finished second in Milan-San Remo to Gerald Ciolek in 2013 and last year, he made a show with his Poggio attack leading to Italy's famous casino town.
Sagan, who knows Kwiatkowski well as they raced together since the junior ranks, said after the loss, "He owes me a few beers."
Sagan faces the same dilemma for Saturday, with rain predicted for the race. If he attacks on the last climbs, he will be marked by riders like Kwiatkowski, Philippe Gilbert (Quick-Step Floors) and Greg Van Avermaet (BMC Racing). Instead, he could save his show for the sprint.
"The secret [to winning]? I don't know, because I've never won it," said Sagan.
"I don't know how to answer now. Maybe I'm going to be more smart in the Poggio, but [I'll decide] in that moment when I'm there, not now."
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