Because Destiny Demands It!

I see a plot hole in your future...I like suspenseful fiction.
And a key part of suspense is making it a very real possibility that the hero will fail, or will only succeed at a horrible cost.
There's also a really easy way to kill the suspense deader than a welk in a supernova: introduce a prophecy in chapter two that outlines how the main character is the Chosen One who will win at everything forever. For some reason, Fantasyland has a surfeit of really good seers who can nail down the details of who is going to defeat the Dark Lord in the gloomy fortress with the magic sword.
The Captain Obvious option is to dispense with prophecy entirely-- there's no reason to go visit the Dispenser of Plot Spoilers Local Fortuneteller in most stories.
Alternately, you could have some fun with prophecies:

Include a faker or three. If there are seers in your universe, or people believe in augury, it makes sense that some people will exploit that to various degrees. It could be someone spouting grand and mysterious nonsense for a fee, or it could be someone really clever who deliberately spreads false prophecies to further their own ends. Knowing the prophecy can mess with people. A number of stories turn on someone trying to dodge their fate, only to take the precise actions that make the prophecy come true. The prophecy has a twist ending. This has been done with regularity, and has to be done carefully to avoid a major audience facepalm. But a clever one can cause a very satisfying 'ah ha!' moment (or an 'oh no!' moment) when the audience and character both realise they were wrong. The prophecy only gives partial information. This gives you room for all kinds of plot twists, as well as potentially misleading the characters. 
There's lots of ways to play your character's encounter with the roving seer or the ancient prophetic text, if you must have them glimpse the future. Just please, no more Destined-to-Win heroes!