Something like a basic written comprehension test on a random 10-K filing would efficiently and cheaply filter out those who are, and aren't, qualified to manage their own money. In fact, I'd wager that it'd probably reject a whole bunch of finance/eco/accounting majors as well.
If you don't know your balance sheet, from your income statement, from your FCF, from your capex, then you probably don't have any business buying or selling financial assets. To anyone who says that this is an unfair statement, I have no knowledge of airplane mechanics, and hence, I probably have no business repairing airplanes. The same reasoning applies to investments.