I think the only bad side of it would be our own reaction to it as a society. I'm not sure what would happen, but there could be chaos. I don't think the aliens would likely be malevolent - I wrote about that here: https://slashdot.org/comments.pl?sid=1630538&cid=31979040
I also think there's ample evidence that aliens are already visiting us (and, I think they probably have been for a long, long time) - I wrote about that here: https://philosophy.inhahe.com/2017/02/04/on-the-subject-of-aliens-and-their-crafts/