Earlier quoted context omitted.
Yes. The shareholders are rent-seeking. They should be taxed as if it was normal income. They don't provide an real value to the company, its output or consumers. For the most part, they are a determent to all outside themselves (specifically their holdings).
Shareholders don't provide value? Then why do companies sell stock? That makes no sense.
The reason stocks are sold is due to cost of capital. A company can make money in a few ways. First is they make a product or service and receive money from customers. Second, they can IPO or some other form of shareholder investments. Third they could finance their needs either with a direct loan or through bond issuance.
Now, most bonds are considered junk if they are from a small company, especially one where people are working out of their garage. This means the debt has a rather high rate (because people think you're going to default). So now you've got to find a buyer (requires middlemen and their costs) that's will to bet on you. Good luck (no seriously I'd prefer this over opening my company to an IPO).
Bank financing is hard to get for pretty much the same reason that bonds are junk. Unless you can show positive cash flow for a few years (you know with your just formed startup and a dream), you probably not going to get a loan. It is due to this that often people, including Elon Musk, self-debt finance via credit cards. Again, ridiculously expensive lending terms.
Let's say you are making money. That's great, you're in the top 40% of startups. You are now constrained by the amount of money you make. If you make 100k a year, but need 1mil to bring a new product to market, we'll see you in 10 years (probably more like 13 with taxes removed over those years).
This brings us to stocks. Find people that are a) suckers, b) chumps or, and good luck o' bearer of dreams, c) actual believers in your product/service. They buy at the IPO price. Your company gets a percentage because the financial house that offered your stock takes a chunk. VCs might cash out after their sale moratorium ends. But after all of this you have a pile of money. That 1mil product is probably doable now. So is an office complex with open floors, and a coffee machine and free lunches and a dog kennel for when your employees just need to feel something that proves they're alive.
You also have an asset to back bonds. So you can, after a small period of time, issue bonds.
At no point did the shareholders add a penny in value to your product directly. They are just there hoping to the FSM that they can leave your stock at some point with a gain. They DO GET TO BITCH. They can have you legally removed from your own company because you have a long view that says in 10 years doing X, Y, Z will increase this companies value 100 fold, but it won't help (probably will hurt) the next 3 quarters.
As a stock holder I can say this about other stock holders. Fuck'em. They get 10-50% return for literally parking their money. As they have more capital related income, they should be taxed as income (outside of reasonably tax-protected vehicles like retirement plans).