Depends on the strategy, if you're just rolling bets to hit the jackpot you won't lose that much, but if you're playing Martingale etc. the jackpot might not cover your losses at all

I was autorolling, I have a total of 600k bets placed on my account, and had a couple of friends join me on a FJ Jackpot night chase 
In total we placed around a million bets, so I was pretty lucky since odds are 1: 100 million during the week and 1 in 10 million mid-week.