You are not alone. A close friend of mine has bipolar disorder, but was able to keep it from friends and colleagues due to a combination of a happy life, strong family support and great personal charisma. No one knew, or even suspected it.
During Covid lockdowns, his business went under, and his marriage began to suffer. Pretty soon he was experiencing manic episodes brought on by the grief/stress of losing his livelhood, and he wasn't taking any treatment because it was in his manic phase that he was coming up with ideas for a new business. He'd be up all hours of the night and completely worn out and depressed during the days.
His marriage ended, he moved out into a working farm which he bought, changed his phone number, and I haven't seen or heard anything about him since.