(This is my first day at answering questions here, so bear with me in case I derp.)
Little self-intro: My name's Zach. Been a born-again Christian believer since early 2002. I've read most, but not all, of the Bible... So I recommend not just blindly taking my word about the Bible, but investigate for yourself as well! The following is my opinion and might not necessarily be true... Though I did study it, prayed about it, and have thought about it a lot, so I feel confident giving an answer!
Is the world safe? (I decided to break up the thread title into 2 parts.)
Short answer: No.
Longer answer: Since I'm just given the questions without additional background or explanation, I'm going to make some assumptions about the question (but feel free to reply asking about a different interpretation of this question!). Since most everyone (I guess excepting babies and some mentally handicapped) on earth realizes there's a chance that someone or something could hurt them someday, I'm going to take the question as, "Is the world safe [when you're living for God]?"
And I would say, "it depends." If what God wants you to do requires you to be healthy, then I absolutely believe God will keep you safe to do it! The third chapter of Daniel comes to mind. The Jewish people were defeated and forcibly relocated to live in a foreign land under the rule of King Nebuchadnezzar (dang, what a long name!). This king made a giant statue and ordered everyone to worship it. But 3 Jews named Shadrach, Meshach, and Abednego refused. The king told them he'd execute them in a large fire. They said, "If this be so, our God whom we serve is able to deliver us..." And the king had them thrown into the fire, but they miraculously remained unharmed! The king and his men noticed, called the 3 to come out of the fire, and they saw that even their clothes showed no sign of the fire!
However, even though this is an exciting story with a happy ending, there are plenty, plenty of cases where people following God have been hurt for it. Of Jesus' 12 disciples, 1 betrayed Jesus and then committed suicide, but the other 11 remained faithful! Yet 10 of those 11 were murdered to their belief that Jesus was God. And the one that wasn't murdered, John, was still tortured multiple times and sent to live in exile on a small island away from anyone he knew for many years. So I think it's pretty clear that following God means it's likely you'll experience hurt in some form, but you can rest easy knowing that if God needs you to stay safe for a time, you most definitely will be!
Now the second half: "I wanna live a happy life!"
Short answer: It depends on how you define happy.
Longer answer: There's this really good book called Desiring God by John Piper. He calls himself a Christian Hedonist. He explains that he's discovered that the most joy anyone can have in life is to be a follower of Jesus. So in his pursuit to maximize his joy, John Piper has become dedicated to, "delight in what delights God." In other words, if you're keeping in mind not just what makes you happy today, or what will make you happiest over the course of a year, but instead are looking at will make you the happiest for the rest of forever, then I heartily agree with John Piper that following Jesus is the answer!
However, if you want define happiness by the more cultural, advertisement-heavy sense (like having a nice house, fancy car, lots of money, etc), then really your best chance is to born to incredibly rich, kind parents who don't expect you to work for wealth, and then hope every day that real life's RNG doesn't screw you over with brain cancer, a car wreck, nuclear warfare, etc... And even then, it seems highly likely that happiness won't fully satisfy you, and death and old age will still eventually rob you, so that's why I think placing the rest of your life and subsequent eternity with Jesus is a smarter bet!