They don't laugh at "us".
They laugh at dumbazz rappers that spend $250k on a single necklace and $50k more on a pinky ring. 99.9% of black people aren't doing that.
Merchants and loan officers also laugh at tall, chunky, loudmouth white salesmen that buy big azz boats, trucks and houses they can't afford.
This idea that blacks folks are bad with money is propaganda designed to make us think it's 100% our fault for structural inequality. It's mostly that our parents/grandparents etc., didn't benefit from the GI Bill, received less favorable terms for small biz loans, got hurt by redlining and other measures designed to limit black wealth creation.
American whites are just as bad if not worse with money. The only groups that are "good" with $$$ are those that simply earn a lot of money and also receive cash infusions from family to buy homes, pay student loan debt etc. Most of us don't get $40k as a wedding present. We have to scrap on our own.
Jews, Asians and Africans just go into law/medicine/STEM and pull enough $$$ down to overcome any potential disadvantages. Those groups are also very small relative to other U.S. populations so there's that. Jews get both minority status and white privilege. Can't really emulate them 100%.