I would just say to Neymar, so what if you lose 1M or 2M, it should not matter to him.
If it was me and the amount was 200 or 300$, I would have cried and thought why I spend all this amount on a single bet, but for the people like Neymar whose one week earning is €1M, losing this amount does not matter to him.
We're talking a million in Euro.
And I'd certainly do something crazy that more than crying if it was me. It doesn't matter to him but me as a pleb sees the entire chunk of that amount and I might reach that amount when I grow older but I'll not spend that within just an hour!
I guess by losing this amount he is being discussed on social platforms and this is also something favors him. If you and me loss 500$ in gambling, no one would listen us or care about us.
What if that's part of another advertising technique for which we saw on how Drake did it before? Seems effective if that's the way but this is likely a genuine loss on him.