I recommend reading the book of Habakkuk, particularly the first two chapters. It deals with this same train of thought. Habakkuk, in a nutshell, asks God why there's so much wrong and injustice, so much murder, etc, and why God is seemingly not doing anything about it.
Habakkuk 1:1-4 The Message (MSG) Version
"The problem as God gave Habakkuk to see it: God, how long do I have to cry out for help before you listen? How many times do I have to yell, “Help! Murder! Police!” before you come to the rescue? Why do you force me to look at evil, stare trouble in the face day after day? Anarchy and violence break out, quarrels and fights all over the place. Law and order fall to pieces. Justice is a joke. The wicked have the righteous hamstrung and stand justice on its head."
God's reply to Habakkuk, in a nutshell, is: brace yourself, because justice coming. This was all on the eve of God using the Babylonian nation as a lightning rod against His people, Israel.
In short, God is not blind. He knows what's going on, sees all the evil, but He is longsuffering, because He doesn't want anyone to perish. He promised to deal with evil and reward righteousness and godliness, and it may seem like He's slacking on that promise, but He's not.
2 Peter 3:9 HCSB
"The Lord does not delay His promise, as some understand delay, but is patient with you, not wanting any to perish but all to come to repentance."
It's just like in the days of Noah:
1 Peter 3:20 KJV
"Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water."
Think on it from this perspective: yes, another day going by means another day evil gets to flourish, but it's also a day wherein the same evil has an opportunity to repent. As for the angels who have fallen, we must simply accept that they are reserved for judgment.
2 Peter 2:4 KJV
"For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;"
2 Peter 2:4 Young's Literal Translation
"For if God messengers who sinned did not spare, but with chains of thick gloom, having cast them down to Tartarus, did deliver them to judgment, having been reserved,"
As for our role in this massive spiritual war, don't underestimate our purpose. Yes, this is an incredible battle with some serious beings on the battlefield, but we, though being in the physical right now have been equipped to do some spiritual damage- read Ephesians 6. Remember that as a Christian, you are on a team- the winning team.
consider this incident in the book of Daniel:
"Then he said to me, "Do not be afraid, Daniel, for from the first day that you set your heart on understanding this and on humbling yourself before your God, your words were heard, and I have come in response to your words. "But the prince of the kingdom of Persia was withstanding me for twenty-one days; then behold, Michael, one of the chief princes, came to help me, for I had been left there with the kings of Persia."
As for the side of good seemingly not winning over evil, Remember the divine perspective. Remember that God is eternal and sees the beginning from the end. Christians do not fight for victory- we fight from victory. We have already won, no matter what things may look like.
God is aware of evil
God is longsuffering, just as he was in the days of Noah, giving man a chance to repent.
God will reward the righteous and godly in due time; the fallen are reserved for judgment
We are in the physical, but we still can make a massive spiritual difference.
Christians are already victories.