Let me take a guess..... you spend more than $2000 of your own money to wager that $332k.. right? How is a reward of $100 worth it, if you lost so much money trying to achieve it? Even if you multiplied it four times as you said..... then you still made a huge loss on it.

I do not chase these challenges, because it is basically designed to reward a few whales..... the rest of the people get a fraction of a percentage of the big amount. Yes, it is a little bonus... for the money you spend on the site.... but it is so small... that it makes no impact on your losses.

Reaching $332k with only $2000 of net loss is very difficult IMO. It's less than 1%, 2000 / 332 000 = 0.6% On which games do you have a such small house edge? AFAIK only blackjack is offering such a small one. But you need to be a very strong black jack player, who never makes mistakes. So I don't know if he is one of them but only few people are able to achieve that IMO.
Guys, losing 1%, or whatever the house edge for the game you are playing is, is never guaranteed. Some times I wish I'd lost only the house edge and other times I'm in big profit after making just a few rolls.
So, reaching $332k with only $2k of net loss is not "very difficult", neither it is "easy", it just depends on luck. You can be in profit of $1 million after wagering $300k. I'm pretty sure there are such cases.
In probabilities this is called variance, basically a house edge of 1% is just the average of what all the players that decide to play that game will lose, but as you state that doesn't really mean that each person is exactly going to lose 1%, some people will lose more while some people may even earn money in that game, but if we were able to add the results of every single one of those players, assuming the pool of the players was large enough, we will see then that the average result of the players losing 1% holds true, and this is how casinos make money even when some of their clients win big.