> Also trusts are taxed fairly punitively

That only reinforces my viewpoint that buybacks advantage rich shareholders.

> your cap gains rate can vary substantially over time

It is 0% (up to like $100k for a couple filing jointly), 15% (up to about $580k), and 20% above that. Income tax has many more brackets than that and they kick in at way lower incomes.

It's true that your income can vary substantially over time. It might be nice to do earn all your capital gains and dividends in retirement. You will likely need less income then to live on and can incur $100k/year in gains and dividends tax-free. On the other hand, remaining invested in a stock that does buybacks during your working years also concentrates your risk in that stock. So people will likely sell anyway and take some capital gains to diversify.

And finally, if we want companies to improve productivity (read: fewer employees) then we can't solely tax labor to fund everything. We have to tax the part of the pie that's actually growing: this is represented by stock prices and dividends.

> On the other hand, remaining invested in a stock that does buybacks during your working years also concentrates your risk in that stock. So people will likely sell anyway and take some capital gains to diversify.

This really undercuts your previous argument that only certain classes of shareholders benefit from buybacks. Now you are assuming that everyone falls into one of the classes anyway.

So we're back where we started: Buybacks benefit all shareholders equally.

> This really undercuts your previous argument that only certain classes of shareholders benefit from buybacks.

If you have so much of a stock that you need to sell to diversify you're still rich.