It's called "Unlucky Stars Wheel" for a reason. But about lucky board and this event, a friend of mine who is ranked in top 20 got two Hashirama's and then got the Kyuubi cloak Naruto this week. All without even paying that much. So I can't say its not RNG, the odds are probably very, very low but I don't think it's hard coded to avoid you. What I mean is I don't think there is some conspiracy going on to scam you.

Me personally I prefer to spend money on something more tangible. Like event ninja you can get for Recharging "x" amount. Its a double whammy because they are good ninja plus you can just dump all that money into power. Take this as a lesson learned, and if you spent that much into the event surely you atleast got a decent redeemable ninja right?