I don't think he said that he's been cheated but about failing it, he did said that. He was just disappointed that he didn't claimed it before and yes, no worries with that as he has seen that those codes already expired and he has to move on already. Anyway, you're right with all that you've said and there's a need for them to be attentive at all times especially when they've been joining giveaways and contests for them to see if they've been rewarded or not.
If that's the case, then it's only the fault of the person who was late to the giveaway. It happens. Why complain about such a circumstance? You didn't make it. Why do you have to make a global problem out of it and curse everyone? It's not worthy of a gentleman. On the contrary, I would just keep silent and draw conclusions from my mistakes, so as not to repeat them later.
Well, lets just say that people actually react to problems or situations in different ways, both in words, actions and dids, this is what makes up different and unique as humans, personally I would blame the user for the outburst, that's probably the best way he thought to react to his missed opportunity, even though he either knew or didn't know that his outburst won't change anything.
The world of cryto currency, which also now cuts around the gambling industry is a very fast moving world, and lots of people miss a lot of opportunities everyday, most especially the active ones, this is why I always tell my friends who are interested in crypto, as well as crypto gambling casino, airdrops, giveaways and so on, that it is mandatory to always be active, because a little sleep or slumber, you just might wake up to discover that you've missed out on a very good opportunity, one that sometimes could be life changing.
So, the user should blame no one but himself for no being online and active to claim his bonus when other were claiming theirs, all he should do is just learn from this experience that both time, opportunities and rewards waits for no man.