The remark ought to be seen as a little bit of hyperbole to flatter and make conversation.
The MIT Airline Data Project shows block hours (door closed to door open) for FAs. On AS in 2015 it averaged 40.8 hours per month. With average speed depressed by taxiing and climb, call it 15,000 miles per month. Do a few flyers rack up more than 15,000 miles a month, AS-metal only? Probably. Average FA to average 75K flyer, though , it's not even close.
http://web.mit.edu/airlinedata/www/2...nes%20Employee