Most small business owners I've encountered, especially those whose business is in its infancy, don't ever take sick days or personal time off, especially not fucking 9 days in a row. Fuck, even most employees of established companies, whether they're scrubbing toilets, hanging out in the C suite, or performing brain surgery, don't ever take time off for being ill, much less nearly two full work weeks. It sucks and is unhealthy, but it's true. She had a stomach virus, at worst, and more likely just made herself nauseated by refusing to deal with her prescription refills, as is her wont. There are people with literal cancer who keep working their manual labor job while on chemo. A guy in my department had surgery on Tuesday and will be back at work tomorrow because in his words, "it's just laparoscopic."
Starting a small business means working doubly hard to get things off the ground. Marissa, like a real small business owner, doesn't have employees to help her with anything. For most people, that would mean busting ass to do it herself, not crytyping on Twitter about her diarrhea.