This is the 7539th most frequent Japanese word.
冒険
Adventure.
The word "冒険" in this sentence is used as a metaphor for the unpredictability and thrill of life itself.
人生は冒険である。
Life is an adventure.
The word "冒険" here pertains to the act of exploring or participating in thrilling activities that may involve risk.
危険な冒険をするのは楽しい。
Engaging in dangerous adventures is fun.
"冒険" in this case refers to the imaginative or inspired sense of adventure one might feel from watching or experiencing something.