Existential risk is a topic that doesn't get nearly the attention it deserves. Although it would be very difficult to eliminate all life on this planet, human civilization is becoming quite fragile, and numerous experts estimate the likelihood that human civilization will not survive another 100 years to be 20-50%. If that sounds overly pessimistic, I encourage you to research the subject and learn why they're so concerned. Here are some great articles on the subject:
Existential Risks by Nick Bostrom
Cognitive biases potentially affecting judgment of global risks by Eliezer Yudkowsky
Artificial Intelligence and Global Risk by Eliezer Yudkowsky
How to Destroy the Earth by Sam Hughes
Risks to Humanity
Some scientists' views of the biggest threats to Earth
"Some people say that the global elimination of poverty will end the nuclear risk, but the U.S. used nuclear weapons in 1945 when it was the richest nation on Earth. People will justify their use. What holds it in check is the lack of knowledge, the degree to which materials are controlled, and deliverability. We are losing on all of those fronts." - Warren Buffett