As far as the negative aspects of blackholes.
That is simply a moralistic veiw of the situation
you can not say that a blackhole is any more negative than a rock in your yard.
I think that what needs to be examined here is the potential destructive force a particular phenomenon can exert.(ps so far as we know there
are no blackholes anywhere near earth so you
need to worry more about the negative effect
of a tornado or global warming.)I think the two
or three entries before envision blackholes
as some huge ever expanding vacuum cleaner
The initial singularity cannot have more mass than star that it evoled from. A blackhole is a region of extremly destructive force, but then
again so is your stomach from the perspective
of the food you just ate