Severe damage to kids mucking about described here:
Is Your Laser Pointer Dangerous Enough to Cause Eye Injury? - American Academy of Ophthalmology
I have given lectures using a one milliwatt laser pointer and it seems entirely adequate for quite a large room.
We have in my astronomy group some green laser pens in the 5 to 10 milliwatt range to use as pointers but we don't let visiting members of the public use them.
I will leave it to those who are pilots to discuss the dazzle and distraction at distances of a mile or more. And it does not even have to be a laser - see here:
https://www.theguardian.com/uk-news/...anglesey-wales