I bet you're really fun at parties. It's pretty apparent you have never done a fed, it takes much longer than 30-40 minutes.
edit: Although it may not contribute to payout directly, you should include actually how much time it takes to complete one fed. Grabbing all the gold bars, the setup process prior to even robbing it, and then driving to rebel and selling and dividing the cash. Due to this, the payout is even worse if you compare it to something direct like meth making. If the fed was something risky, but you actually could get out rather fast it'd be more worth doing.