That's what I did. But I got lucky and got it in 10 mins of letting it autoplay. There all all kinds of strategies out there. Some say you should close the gate and get some sort of "beginner's luck". Some say you have better luck if Noel is your controlled character. All say you should play when the machine is in the right mood. Think it's summer's day.
You don't have to be up by 7777 coins, you just need to win 7777 coins in total (so you can go in with 10000 coins, say, and get lucky coin when you're at 3000) and you can do it in multiple sessions. But be sure to get the serindipidous trophy 1st before playing slots.
It doesn't reset, but it's not like with chocobo racing you can't get back your net loss in coins in no time anyways
This. I lost a ton in coins from the slot machines before realizing my mistake. People make it sound like it'll take forever to win with racing, especially if you lose a ton, but it took almost no time at all to get enough coins for the trophy. Just had to take the time to train the Silver Choco.
I found that highly offensive Official Aveline de Grandpre of the ACIII boards