Ted Kaczynski sent mailbombs to specific people in academic circles who he believed were accelerating fields of technology that was leading to the downfall of human society as he saw it. They received individually crafted bombs addressed to them in an attempt to kill them and dissuade others in the field as part of his campaign of terrorism.

Timothy McVeigh bombed a federal building with a large truck bomb. His target was federal employees in general, but it was more a 'to whom it may concern' attack that he viewed partly as revenge for the Waco and Ruby Ridge seiges and partly as the opening salvo and catalysing event that would precipitate more civil unrest against the fed and lead to more violence and destabilize the government, chaos in which a violent and racist element would be able to take power and hold territory.

Honestly, probably good, if you have a natural tendency to avoid cognito hazards.

If on the other hand you are an intellectual sadomasochist, just spend about an hour researching each of those names.