Person A has a net worth of 2B Person A has a loan at 500M backed by their holdings Stocks drop 50%, Net worth is now 1B Person A buys $500m of stocks Market Recovers 100% Person A now has 2B original holdings and 1B gains, $500m owned = 2.5B

Very simple example, and not the only way to do it - but people need to remember net worth being 500B is not 500B in the bank, and at some point the number doesnt matter