Some corporations are rich because we the ordinary working class make them rich. We have allowed ourselves to become dependent on their services, for example;
mobile phones, something that, 20 years ago did not exist and was not necessary, is now essential. Much can be said of banking, 40 year ago ordinary working men did not need a bank account. Now we have to have all sorts of financial service products just to survive day to day. What is morally wrong with trading with people who voluntarily engage with you?

On the other hand, some corporations have become rich because of government contracts, the most notable ones I'm thinking of are "defence" contractors. They are also funded by the ordinary working people, but in this case 'we' have not chosen their services, our masters have, and paid for them with 'our capital'. This is clearly morally wrong!

An obvious fact, often overlooked is; as the corporations derive all their capital ultimately from the ordinary working class, any tax on the corporations is ultimately a tax on us, who are dependent on their services.

Their is no fair tax: all tax is theft.