There is a difference between a risky endeavour and certain death.
Not really. There are some fields of endeavor that are incredibly, inherently, irreducibly dangerous. Space travel is one of them. There's not much of a gap between, say, a 25% chance of fiery or icy death and a 100% one. It's certainly not the same as the difference between driving to work and taking flight in a space shuttle.
Instinctively, we accept risk of death when the reward justifies it. Being a successful astronaut is rewarding - in terms of prestige if nothing else.
Have you ever listened to an astronaut? To a person, they'd all return to space in a heartbeat if asked. Their motivations have very little to do with personal prestige - they just want to return to the stars.
A compelling scientific mission that will add to human knowledge is arguably more rewarding for civilization, but not for the individual who dies, and the reward is too abstract for our instinctive response.
There's no place for instinctive response here. My instincts are that climbing into a tin foil capsule on top of a fuel tank filled with 5 million pounds of kerosene and LOX is insane. And yet people have worked out the risk-reward calculations and decided that hey, this is a good thing we should do.
Plus it's not obvious that there is a lot that live astronauts can do that do that robots can't.
Well, other than collect data on the effects of deep space travel on human physiology, and the ever-present "anything a robot hasn't been specifically designed to do".
Simply 'being first' will not be a compelling reason for others to enable suicide, or be left to watch it helplessly from a distance.
Then use any of the other millions of reasons why human space travel is something we need to start figuring out and practicing.