I saw on this thread, “Discover card $500 cash back for $3k spend per month for 6 months – existing user” that a targeted Discover promotion is offered if you spend a certain amount in a defined about of time. Some are posting creative ideas to send money which would increase the monthly spend, but they would still be short.
I think they should go a Discover partnered retailer and do cash back. Do some shopping, ask for cash back (which posts as a purchase, and not a cash advance), deposit cash into the bank, and repeat the process to hit $3,000 per month in spend.