Borrowing against stock is mostly something for HNW people.
> shareeholders benefit from reduced share count because it increases their claim on future profits
So...dividends? Or when they eventually sell? What if I never want to sell?
A: Hold $10 of stock. Buyback of 1$ per share. You're left with $10 of stock. B: Hold $10 of stock. Dividend of 1$ per share. You're left with 9$ of stock and $1 cash - taxes payed. Once reinvested you have $9 + (1 * tax rate) in stock.
You're making two mistakes: One is thinking that dividends are magic money that do not cause share prices to fall in exact accordance with the distribution and the other is that buybacks lift the share price somehow (they do not, see Modigliani-Miller).
At least if your broker offers decent margin rates or you sell boxes.
Well, also, your 401k and IRAs are probably superior to this strategy and can't be used as collateral as they're protected in bankruptcy. So it's not worth it until you fill those up.
But it's way riskier.
> At least if your broker offers decent margin rates
I guarantee you no retail broker will give you the rates Elon's broker gives him.
> you sell boxes
I have to guess you mean "box spreads". This is an advanced strategy and again more likely used by HNW people.