There are many structural reasons why Europe doesn't produce gigagrowth oligopolies like the US. EU has a highly fractured internal market that is more difficult to dominate, EU is not bathing in reserve currency windfalls to be thrown all around and EU doesn't have as ruthless foreign/trading policies.
Also there's a difference how "risk taking" is portrayed in the public discourse. In US success of companies are seen more as result of risk-taking of individuals, whereas in Europe success its seen more as resulting from collective effort, and founders/CEOs of successful companies are not lauded as heros, or are even usually especially famous.
