Certainly...just like "bad people" can become "good" should they so choose.....(not counting the criminally insane ones, of course) Various things corrupt an individual. Power, Greed, Money, Fame, etc. Those same people could be your best friend one minute and if they aren't careful, they don't know you the next. Doesn't make them bad really, just a jerk.
Of course that can happen. If a person is exposed to bad people or unnecessary struggles, it can make them take out their anger and despair on people around them. Try not to judge who ever it is your talking about. For all we know, their parents could be beating them.
Absolutely. The inclination to do wrong is part of being sinful. The apostle Paul stated at Romans 7:21-25 "I find, then, this law in my case: that when I wish to do what is right, what is bad is present with me..." Paul was subject to the effects of sin on the imperfect flesh. We can relate to him because all of us are imperfect and have to face similar struggles every day. Moreover, there are many distractions that could divert our attention and take us off ‘the cramped road leading into life.’ (Matt. 7:14) However, the situation was not hopeless for Paul, and it is not for us. To learn more see the article "For Life and Peace, Walk in Accord With the Spirit" on jw.org
yes, we see all kinds of accounts in the Bible where someone was in God's favor then turned bad. Look at Satan - he was not always Satan -however, he decided he wanted to be just like God and he turned wicked taking 1/3 of the angels with him. -Revelation 12:9
The Scriptures indicate that the creature known as Satan did not always have that name. Rather, this descriptive name was given to him because of his taking a course of opposition and resistance to God. The name he had before this is not given Therefore, the one becoming Satan was, when created, a perfect, righteous creature of God. He is a spirit person, for he appeared in heaven in the presence of God.