Well every great invention always were double edged sword. But what made them acceptable are their more positive features rather than negative. Same can be said about technology, it has the power to destroy our lives if we allow it to, on the other hand with the help of technology we are developing exponentially. So, it;s a matter of choice.
But I think the reason for concern is Artifical Intelligence. Technology shouldn't ever get control over humans. People are allowing the use of AI, which is actually pretty cool for now, but if we talk about future then there is some reason for concern.