Except they are using it as collateral to accumulate excessive amounts of wealth, essentially replacing their income, tax free.

Which is why the first commenter mentioned the tax should be used on unrealized gains that are used as collateral. Not just the unrealized gains themselves.

Also, yea, when they sell, they pay a tax. Just like everyone else. That is a completely separate instance of wealth accumulation that is unrelated to the wealth accumulated by using those gains as collateral.

Don't like it? Don't buy stock and earn your money through income from a job instead. It's that simple.

Though tbh I think this entire discussion on share and stock is pointless. Profit paid to shareholders is wage that should have been paid to a worker; if you don't perform labor for that company, you shouldn't have any entitlement to the profits made from that company.