The past is known, the future is not, but he who knows the future will inevitably do some things making that future not coming to pass.
In the end we can only hope a time machine never comes to be... Nothing but trouble can come from that that. Not only paradoxes. Some quarrels humans fought over for thousands of years have stories that have always changed for the benefit of the parties involved. A time machine allows us to see the initiating events the way they really happened without any clouds of old propaganda. Some wars and some views on religion will inevitably be irrefutably debunked.... I am not quite sure if humanity is ready for those truths yet, whatever the truth may turn out to be (for nobody knows. There are a lot who claim to, but those are either liars or people who need to face the facts the way they are). I deem it very well possible the truth about those things may not be what you wanted it to be, and once you know I'm quite sure you'll wish you never came to know.
So let's stay in the present. It may not be the best time, but at least nothing drastic can happen. No don't start about 2020, COVID-19 or killer hornets or whatever. The trouble a time machine brings, will be worse than all misery humans faced over the entire course of history altogether. Of that much I'm sure!