Bipolar is terrible. People don't understand how little control a person has. The worst part might be the regret from all the mistakes you make and people who get hurt when you lose control. Many people choose to cut you out of their lives and decide you're more trouble than you're worth. The regrets make the depression worse. Sometimes, the manias don't feel high enough, or long enough, to balance out the bad.
It's hard to keep a job when you can't be stable. Disability is there, but they make it hard to get in some places. The idea of having any sort of enduring relationship seems impossible as well. Raising a family? Passing on the illness sounds terrible and being stable enough to raise children sounds like it couldn't happen. It can be distressing to feel like normal life is an impossible standard.
The there are the mixed episodes. It's like bipolar function along two axes. One spectrum from high energy to low energy. One from manic joy to depression. The mixed episode with high energy and depression has been said to be the most likely time for suicide. Sometimes, it can feel like just waiting for the energy to go through with it.
On a different note, it can seem like a divine madness. All the chaos of the world is entwined in the experience. Mania can feel like going berserk. If there is a god, it seems wrathful, angry, loving beyond measure, merciful, etc. Something about it reminds me of the phrase "man would go mad to know the mind of God."