The 18-year-old has now reflected on the decision that took him away from home at 14 and helped set him on the path to the German champions' first team.
In an interview with DAZN, the Bayern Munich forward explained that his family were not immediately convinced by the prospect of him moving to Munich, particularly his mother. Karl, however, already knew which club he wanted to join.
“My parents weren't so convinced about it, especially my mother. But from the beginning, when Bayern came in, I said I wanted to go there. […] My parents weren't really on my side. I had a few other offers. I said I was going to do it.”
Karl moved from Viktoria Aschaffenburg into Bayern's youth system in 2022. The decision meant leaving his familiar surroundings and moving into a boarding school, but he was determined to take the opportunity.
The young attacker has since progressed into the senior squad under Vincent Kompany, becoming one of the club's most promising prospects. His development has made the gamble worthwhile, even if the transition initially proved difficult.
Karl has previously spoken about experiencing homesickness during his first weeks away from his family. Settling into life with the other young players helped him adjust, and the football environment soon became a positive experience.
His rise has also brought greater attention, with the teenager establishing himself as a regular part of Bayern's first-team picture. Yet his recent comments reveal how much of that journey depended on a decision made before he was old enough to appreciate where it might lead.
The interview also touched on Karl's childhood connection with Real Madrid. He was reminded that he had worn the Spanish club's shirt at the Santiago Bernabéu when he was around 10, prompting him to explain how he came to visit the famous stadium.
“It was a football camp. There were two levels. First, people signed up, and then the best players went to another camp. The best players from that camp were then invited to the Bernabéu. It was that kind of football camp,” he said.
The memory provides a glimpse into Karl's early football experiences, before he committed himself to Bayern's academy. His appearance at the Bernabéu was part of a development camp rather than evidence of a formal Real Madrid transfer pursuit, and the young player did not elaborate on any deeper connection with the Spanish giants.
Instead, the clearest message from the interview was his conviction about joining Bayern. Despite having other options, Karl insisted on following the opportunity he believed was right for him.
That decision required his parents to accept a move they had initially viewed with caution. Four years later, Karl's emergence at Bayern has given the family a very different perspective on the choice.