Let’s assume that no supernova is imminent in our little quadrant. I think the science supports the notion that a supernova in this area would be exceedingly rare. So, let’s likewise assume that we have millions of years left... in our little quadrant. There’s one, and we’re the only example we have.. So far.
That’s just supernovas. Earth has had five major extinctions, and several partial extinctions.
“Although there are 10—14 million species of life currently on the Earth, more than 99 percent of all species that ever lived on the planet are estimated to be extinct. Extinction occurs at an uneven rate.”