SeagullWatcher have 70,362,198 EP and SED 240,503.
Teory he could get a max EP with all bonus Cards and get +200% (from most dammage and last hit) of
7.02 * 240,503 * 2 * 3 /100 = 101300 EP per hour.

Event last for 14 day so highest teoretc EP for him at event would be
14 days * 24 h/day * 101,300 EP/h = 34 M EP without using Pudding. To ge this he need max bonus all the time and to play 24h per day for 14 days.
70,362,198 - 34,036,754 = 36,325,442 from pudding.
Each pudding give max 50,649 EP. He spend at lest 718 puddings.
More likely he spend 800 puddings and each pudding just cost 1$ each.

On top of that he must have spend another 2-300 $ to get all the bonus Cards.

Maybe I misunderstand someting but to me it looks like he have just spend over 1000$ just on one event.