I have long believed that we are likely to develop technology, or technologies, that will accidentally cause our own extinction, as well as those of other species. I would say we are already on the way, if you look at such things as decreasing sperm counts in men, and increasing rates of childhood cancer. We are continually putting increased amounts and kinds of pollution into our environment, many of which take decades, even hundreds of years to break down. Combinations of some chemicals can have a far greater effect than would be predicted from their individual actions.
Scientist are currently developing a kind of antibiotic that could do the job fairly quickly. If it gets into widespread use, and bacteria develop a resistance to it, as they have to all other antibiotics, they would also be immune to our own bodies' defences against bacteria. It is claimed that bacteria will be unable to develop resistance to them; of course, our technology always produces side effects we didn't foresee. They say they will test that bacteria will not be able to develop resistance before they put it into widespread use. But how can they guarantee that the bacteria will not eventually do so?
If we manage to survive direct effects from our own technology, I believe they might still be our downfall. I expect that we will eventually develop a dependency on technology for our survival. Eg., the antibiotics such as the ones mentioned above. Actually, we have already started doing so. Over a long period of time, human bodies will become less able to defend themselves against bacteria. When mutations occur that weaken our immunity, those that have them do not die because they are treated with antibiotics. So, the genes will continue in the gene pool. Many women may need artificial hormones to conceive and carry a child to term. Our bodies will become weaker because of dependency on machines, etc. There will come a catastrophe, such as severe global warming, or a hit by an asteroid, that might not kill everybody, but would devastate the planet so much that we might lose the technologies on which we have become dependent for our existence. The combination might well do us in. Societies in the past have lost knowledge of technologies. How many of us know how to mine ore, and do all the steps necessary even to make a simple ax, much less something like a car? But there will always be those who tell us, for the sake of short-term profits and convenience, that we needn't worry about such things until they have been proven without an eyelash of doubt. Of course, by then, it will be too late.
The existence of our species, with its ability to understand the world, and appreciate the wonder of the universe, is wonderful. But, since we seem to be unwilling or unable to refrain from devastating our environment, on which we depend, I guess we have to accept that if we cause our own extinction, we will have proved that we did not deserve to continue.