to be fair, i think the event is depends on pure luck, it has a very low chance to get the jackpot but the chance is there.

i have spent 40k coupons in the event in feb but i still didn't get madara ten tails, but my power increased 30k+ which im happy about and also i've seen ppl get the jackpot with 1000 coupons.

so you could say it's really depends on your luck, i will definitely try again when it comes together with fuku, it's still a pretty good event for increasing power =D