Holders Madrid take on Bayern Munich in the semi-final first leg on Wednesday, in the third last-four encounter between the teams since the 2011-12 season.
The fixture is the most-played match in European Cup or Champions League history, with the teams having met 24 times previously, each winning 11 times.
Madrid knocked out Paris Saint-Germain, who smashed the world transfer record to sign Neymar in a bid to bring them closer to the title, in the last 16, while Manchester City, the most expensively assembled team in history, lost 5-1 on aggregate to Liverpool in the last round.
Kroos has won back-to-back tournaments with Madrid, having been part of Bayern's treble-winning side in 2012-13, and he believes such success underlines why no amount of money can guarantee success in the tournament.
"You can't buy a Champions League trophy. If that was the case, we would not have won it so much," he told a news conference when asked why Madrid and Bayern are so frequently in the latter stages.
"It's special for a team like Madrid. We have players in condition to play at the highest level. If you have a lot of players with that experience, in these difficult moments, you know what you have to do and you don't lose your nerve. That's what takes us so far.
"This is the only chance we have to win a title. It was similar two years ago and we did it in the end. We're very motivated: winning it three times in a row is something unique.
"We had PSG in the second round and Juve in the quarter-finals. It's not the easiest road."
Kroos believes Bayern have improved throughout the season under his old boss Jupp Heynckes, but he has vowed to "wipe out the good vibes" of the Bundesliga champions.
"I expect a strong team. It's the semi-final of the Champions League. Bayern are in good form and there's nothing more to say," he said.
"They won the league quite early, but they don't give the impression that they've let their rhythm drop. I think they're in better shape than last year: they had absences then, they didn't have Robert Lewandowski in the first leg.
"Expectation levels at both clubs are similar – you set out to win every competition. Playing in the Champions League is a special motivation for us, as whoever wins in the end can call themselves the best team in Europe. Bayern will be just as hungry as us.
"With Heynckes, they play more as a team. There are good vibes in the team. We're here to wipe out those good vibes."