I have seen people losing tens of bitcoins on gambling, literally millions of dollars. So if they are willing to lose millions on gambling, shouldn't be weird to invest a few bitcoins on fun tokens neither.
Would be logical comparatively, the cashback on million or more would be over 10k a very nice bonus given for what you'd do anyway. I'll never get a 'free' 10k because I'm not gambling that amount but if you are then the cashback bonus is literally worth more which supports the FUN token price itself.
I always figured the token price has some support coming from its reflection of ongoing gambling, it does make sense to hold some. None of the tiers immediately give this bonus but I would characterize it as quite generous as giving 70% of the benefit within only 30 days.