There are risks for inside and outside cats. One is not better than the other it all depends on circumstances (Do you live in the country or the city? Are there predators in your area? Do you live next to a busy street? Are there non taken care of cats in the neighborhood? Etc.). Inside cats can become obese due to lack of exercise. This can lead to joint problems, kidney disease, diabetes, and other health problems. Outside cats can be killed by cars (by accident or on purpose), animal predators, humans, poisons, and coming into contact with other sick cats.
It’s all about prevention. Make sure your cat gets enough exercise, put up a kitty proof fence or enclosure so kitty is safe in your yard while it keeps predators out. Make sure your cat has identification on even if it's an inside only cat because they can escape. Introduce your cat to your neighbors so they know it's yours. Make sure your cat is fixed (there is no excuse it only costs about 40 dollars and less if it’s a male because the procedure is less complicated). Make sure your cat gets check ups at least once a year, and make sure it’s vaccines are up to date, etc. Don’t keep a cat inside and not let it get exercise to where it gets obese. Fat is not cute it’s deadly and it shortens the cat’s life span. Don’t let your cat outside if people go 60mp right out your door. You know the risks of your environment and you are the ultimate decision maker because you know better than the cat.
I do disagree with the fact that outside cats cant live a long life because one of my cats is an outside only cat and she is going to be 15 this July (I live in the country and the yard is safe)!
Good luck with your kitty and again it all depends on the circumstances of your enviornment.