In a cash account every purchase must be paid for with settled funds and sale proceeds are only usable once settled, which limits how often the same capital can be recycled.
A cash account extends no credit. Under t-plus-one settlement, proceeds from selling a US stock are available the next business day, so the same dollars can typically be redeployed once per day rather than many times.
The advantages are real: no margin interest, no pattern-day-trader-rule restriction on the number of day trades, no risk of a margin call, and fully paid shares kept in control under rule-15c3-3. Many small accounts trade this way deliberately.
The cost is discipline around funding. Buying with money that has not settled and then selling again produces a good-faith-violation or free-riding restriction, and options assignments can land in a cash account with no borrowing available to cover them.
Original diagrams for the ideas on this page. Illustrative, not real market data.
Margin and leverage. A $5,000 deposit can control a $100,000 position, which is 20:1 leverage. Because the loss is measured on the full $100,000, a 2.5% move against you halves the deposit and brings a margin call, and a 5% move uses all of it.
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