After Ben Solo/Kylo Ren and his merry band, the Knights of Ren, slaughtered all of Luke Skywalker’s students at his new Jedi academy—we saw a flashback to that in Rey’s Force hallucination in Star Wars: The Force Awakens—the older Jedi went into hiding, and we’ll hopefully find out why in Star Wars: Episode VIII.
I think Kylo Ren and Supreme Leader Snoke certainly qualify as “the wrong hands.”
It’s also been rumored that during his time away, Luke came across something that “put into question” everything he knew about the Force, and now he’s determined to recover the practices and knowledge of the ancient Jedi so he can properly rebuild the Order.
One option is that he did this because of guilt or to mourn, to keep people safe—wherever he goes, people seem to get hurt, and so if no one is around him, there’s no collateral damage to be done.