The boss spends the money and takes the risk. Your risk is screwing up and getting fired, not losing millions of dollars. Easy enough to get a different job if you don't like it.
Risk is a cop out. The people taking these "risks" are, more often than not, very wealthy and their stake in any given venture is negligible. Bezos isnt putting his livelihood on the line to start a new business. Not to mention due diligence, insurance and the ever present corporate welfare machine (bailouts, tax cuts, etc.) reduce the risk to investors to the point that is effectively useless to consider it a risk at all.
And what about the risk labor takes every day? Commuting to work in their own vehicle introduces the risk of a life altering/ending accident. If they moved to get the job they're in they're risking a lot. The neighborhood they live in may not be safe, their home could be poorly maintained or pose a health risk, the school their child would be going to may not be good, their boss could fire them on a whim, they could become injured due to unsafe working conditions, the company health insurance could be terrible and not cover anything, and many more risks individuals take in order to eek out a meager existence. People.get fired for bullshit all the time. It's not just screwing up. Hell, you can be an exemplary employee and still wind up on the street due to budget cuts, mergers, or the company just disappearing one day. The worker takes on much more risk than the business owner ever will.
Instead of defending the excess and privilege of the wealthy, why don't you ask yourself what you're getting from this arrangement? The odds are not in your favor, and the system is designed to make it incredibly difficult if not impossible for you to access the quality of life you think you can obtain in a capitalist system
See? Boss Man is putting in big risks. If he loses millions he might only still be a billionaire.
Me? Well if I lose my job I'll just become homeless and destitute. I'm barely risking anything.
Thankfully I just remembered that Boss Man sold shares of his company to other folks so he doesn't really have any risk at all! Phew! Sure am glad that's working as designed.
Nah, it's not uncommon in the trades in the US to expect workers to bring their own tools. It's bullshit, but unfortunately we've normalized lots of bullshit here.