Capital Appreciation
Capital appreciation is growth in what an asset is worth as time passes. Most rental investors wait for it from the market. BRRRR forces it: the rehab raises the property from a distressed price to a finished value in months, and the refinance turns that gain into cash. Forced appreciation is the mechanism the whole strategy runs on.
On the default deal, $300,000 of purchase and $60,000 of rehab become a $500,000 appraisal. The $108,650 of equity created, ARV minus total project cost, is appreciation the investor manufactured rather than waited for.
The refinance monetizes it without a sale, which means without selling costs or capital gains tax. Market appreciation after the refinance is on top, and leverage magnifies it: a 3% rise on $500,000 is $15,000 against $27,600 of cash left in. It also magnifies a decline, and an investor with 75% loans on every property has little cushion when values fall.