Gareth Southgate has praised winger Jadon Sancho for making the decision to join Borussia Dortmund.
Sancho, 18, moved to Dortmund from Manchester City's academy last summer in a €7.8 million deal and has become a regular starter for the Bundesliga club.
"A few years ago we still had players in Italy, the best league in the world back then," Southgate told German football magazine kicker.
"But now our league is the strongest, and therefore it's comfortable for our players to stay here and not prove themselves elsewhere. But that's also a danger that young players earn a lot of money but don't play.
"Jadon Sancho took a different path. At Dortmund, he plays in front of 80,000 people every fortnight. He must perform under pressure. He plays against men, and that's different to competing with players of your age group."
Winger Sancho has spearheaded a larger wave of young English players attracted by the Bundesliga.
West Ham defender Reece Oxford spent last season on loan at Borussia Monchengladbach, who also have Mandela Egbo, 20, on the books and have signed Keanan Bennetts from Tottenham Hotspur.
Everton attacker Ademola Lookman impressed at RB Leipzig during his loan spell earlier this year, and they hope to sign the 20-year-old on a permanent transfer.
England have the third-youngest squad of the 32 World Cup participants, and Southgate said he wanted the group to develop "a big club mentality" in Russia.
"Roy Hodgson started this at the European Championship, and we'll continue on that path," he said. "We could have also selected older professionals, but we wanted to instead bank on those who have the potential to achieve world class in the next couple of years.
"I have not selected anyone I don't believe in. Okay, maybe they are not ready to win the World Cup yet. But we can surprise the people and make a deeper run than a few expect. It's an investment in the future. We see it as a proof of our development.
"Success like we had with the under-20s, U19s, U17s, boosts the confidence. That's what distinguishes the Germans, for instance. They walk onto the pitch and believe that they can win it. That's a big club mentality. We need to get there with England -- it's important to not be afraid."