Most people with bipolar, like myself, don't shop for shopping's sake; it's because they want to take on a new project or make a major change in their life. I'd buy things like homebrewing supplies, a project car, or athletic equipment. It all either gets returned or starts sitting around a month later, when things get worse.

Sometimes, the projects you failed at eat away at you, daily proof that you are as big of a failure as you think you are, marking your failure as a person. When it's already hard to get out of bed, having to walk past hallmarks of your incompetence makes it even harder.

Rinse and repeat a couple times a year.

That's what mania is for me: a surge of confidence in myself, visible to others as pressured speech and hyperactivity, occasionally leading to irritability. It varies from person to person, though.

Based on stories I've heard/read about manic spending, each person/episode can be different. Having said that, a common thread in many is some delusion of grandeur that could justify the expenses were it not a delusion.

Example I've heard: buying all the tubes of a certain kind of paint in an art supply store in anticipation of doing some huge project. The project realistically would've taken years to complete & their delusion was they were an unnaturally fast artist. Once they snapped out of it, they realized the work they'd done so quickly was shoddy, at best, though they couldn't tell in the grips of mania. They returned most of the unopened paint the next day.

I have mild bipolar myself so I definitely know that exact feeling, though I've never acted on the urge to spend tons of money (yet). That delusion of starting a grand project that would maybe feasible but take an insane amount of work can consume me fairly often.