Executing barrel rolls at Mach 1.5? Nothing. Bearing down on an enemy MiG with two more on your tail? Child's play. Being responsible for the aerial safety of the Leader of the Free World? Piece of Cake. Having a bag strapped in your suit so that you can go potty? Ye—wait...
Being a fighter pilot involves boatloads (or planeloads) of stress. Enlisting in military service is considered to be one of the most stressful jobs in the world, and fighter pilot is one of the most stressful jobs inside the military. Even if we set aside the fact that you are quite actively risking your life every single time you strap into your jet, there are still a bazillion other factors involved that would stress anybody out.
First, there's the sheer cost of the (taxpayer-funded) machinery you're responsible for. Then there are the lives of all those on the ground or aircraft carrier beneath you as you take off, land, and fly around in a 20,000-lb. hunk of metal and jet fuel. You're unlikely to be the only one flying, so there's the safety of your squadron to think about if whatever mission you're flying goes haywire.
Oh, and even if all of that goes swimmingly (flyingly?), being barked at day and night by your superior officers is not the most fun thing to experience.
And did we mention the mechanical outhouse you'll have attached to your waist?
If you want to become a fighter pilot, we whole-heartedly support you. We're huge fans of anyone and everyone willing to risk life, limb, and stomach contents to serve the country. You know who else can lend some support? The base's therapist, who will be only a mayday away.