MSTR also produces some income. That income is multiplied by the P/E ratio at 30:1 currently. So $1 of income winds up producing a $30 valuation increase in stock price. When the stock gets overvalued, Saylor can issue more stock and purchase more BTC.

Furthermore, like in this example, Saylor can borrow money and use that money to buy more BTC.

These are all things that an ETF can't do....since an ETF is a purely passive. Basically saylor has turned every accounting trick possible with a public company into a play to acquire more and more BTC. So buying MSTR is a bit like buying a 2x long btc option.