It would have been worse if it was now items exploding at ungodly levels off of monsters. That would have required a rollback of some level. Be glad it was only exp.
If Arwoo said it ain't happening, then it ain't and you spent 20k NX on a gamble, and lost. That's the consequence of gambling, you might actually lose.
30 minutes is more than enough time to get a rare drop like the Black Bean Mark, Dominator Pendant, etc. that are total pains in the rear to get to drop at all.
Choose your words more … (more)carefully before you realize that rollbacks are not always good things. Besides it only affected EXP, it's not like every monster way exploding items everywhere... get real guys. (less)