The laws underpinning and protecting their ownership, as well as the institutions enforcing them, are historical holdovers and were never truly legitimised. They also largely go against justice, freedom and the pursuit of happines, which they largely champion as their goals.
At the end of the day because the assumption that it shouldn't be any different for a business is flawed. And specifically because we live in a reality where this assumption is largely taken as truth and as a result laws get written by Musk Bezos Koch Gates ... and / or the companies they use to do their bidding. Which often enough have very bad outcomes, and are obviously bad laws, not only in hindsight.
While they are supposed to be written by the people for the people. Democratically. The Private company in this way wields authoritative Power over it's employees and with this power it often enough opposes or distorts the will of the people because the few owners get outsized control over the actions of many workers customers and so on. As such if there isn't a limit to private ownership of Capital/The means of production/Business there can never be anything more than a hollow democracy, a democracy where the word is used to describe itself but the spirit of the word can never be reached.
We are on lefty Memes here so a bunch of people likely want a less hollow and more true democracy in this sense. Which is why it should be different for a business or at large scale.
Yes the ones that draw the largest benefit from a society should contribute the largest amount back. If there is infinite growth for some and infinite servitude for others the social contract is breaking, in this way it's much more reasonable to actually use taxation instead of just standing by while the society that all this wealth was extracted from takes violent revenge to their oppressors.
Without the rest of us billionaires couldn't exist to begin with, so if their wealth starts breaking our governments, our communities, our collective self determination, which they currently are doing, we naturally should remind them that they are nothing without the rest of us. And yeah the taxhammer is likely the more appropriate tool than the guillotine or the Molotov cocktail.
Their wealth presupposes a largely peaceful society, why should we let them break it. This is for example why GG Art 14 has
(1) Property and the right of inheritance shall be guaranteed. Their content and limits shall be defined by the laws.
(2) Property entails obligations. Its use shall also serve the public good.
written back to back in the same paragraph, the obvious implication being uses of property that go against the public good may be curtailed by the law.
Because they didn't make the business. If you started a business would you be happy to give away that ownership to every new employee you hire? If so, that's your choice, have fun.
So it doesn't matter to you that you had to spend millions on startup costs, and that the business probably won't make money for a year or two, you keep that all to yourself, continue to pay employees, and give employees equal ownership?
Ummm... most companies are like that, it's very rare to have no startup costs and profits immediately. I would hate to think the options we would be stuck with if food and drinks were only what the government decided to support.