Stress
In a constantly changing and unpredictable market that becomes less and less profitable every time someone creates a new iPhone app, you're going to get a few gray hairs at best. We hate to break this to you, but music producers are pretty expendable. It's going to still be competitive even after you've "made it."
You're either freelancing your way into staying relevant or you're working based on a label's contract. No matter what, you're going to have to work hard to maintain relationships between artists, labels, managers, and sound engineers, while also proving yourself worthy of your success.