it's not like large companies aren't subject to layoffs
Precarity is a defining feature of the worker's condition under capitalism, yes. That doesn't mean that there isn't stratification on how precarious the situation is for individual workers. It goes homeless < gig work < temp work < small company < big company
don't forget that there's a similar risk of negative money for the owner
I'm not discounting the risks taken by small business owners. However the risks to them is a damaged investment portfolio. The risk to workers is a loss of livelihood.