The October 7, 2023, Hamas attack on Israel marked a pivotal moment not only in Middle East security policy but also in the global Islamist and particularly jihadi propaganda landscape. This article examines how the ensuing digital “victimhood-revenge” narrative rapidly spread across platforms like TikTok, fueling a new wave of radicalization among adolescents in Europe. Drawing on six European case studies from 2023 to 2025—including foiled and executed attacks in Vienna, Solingen, and Zurich—this article identifies a recurring radicalization pattern involving emotionally vulnerable, digitally native individuals exposed to algorithm-driven Islamist content in social media, but predominantly on TikTok. The analysis conceptualizes this process through the lens of a “Virtual Caliphate Complex” and explores TikTok’s role as a low-threshold gateway into extremist ecosystems. By analyzing cross-platform mobilization dynamics, aesthetic framing, and the hybridization of lone-actor terrorism with online support networks, the article underscores the urgency of adapting P/CVE strategies to algorithmic environments. The conclusion suggests possible policy emphasis on content moderation, digital literacy, and platform accountability—particularly in the context of the European Union’s Digital Services Act legislation. The article contends that today’s prevailing Islamist radicalization pattern reflects not only ideological motivations but also youth-online-culture dynamics and algorithmic influence.