Originally Posted by
Radar
The way I see it, anyone can cause serious harm and destruction with commonly available items, yet very, very few people try that. For one, most people are not sociopaths, but even those that are, think of the consequences as those kind of deeds are severly punished. The more dangerous would be subtle spells like mind reading and control. Clever and manipulative people can be dangerous even without magic. If they got spells reflecting their personality and desires it could cause huge problems. It is also a matter of being able to catch magic criminals and so on.
And even if it was possible to ramp up everyones magic resistance, it is not nearly enough, since it is very easy to circumvent it: magical explosives could still destroy buildings and being buried under ruble is not at all magical. Simple telekinesis could be used to slip some poison or mind-altering substances to someones food or drink and so on. Remote viewing spells like Sarah's do not even rely on affecting humans and are still dangerous in wrong hands.
It is always possible to adapt to new circumstances as humanity did for thousands of years, but this takes time and there will be a lot of unforseen problems coming up.