I am beginning to think that the only time a gambler gambles for fun is only when he gambles with what he can afford to lose. In this case, a gambler has $10,000 as his savings, and he gambles with $1000 down, he or she won't feel sad when they lose it (it means they gambled for fun). But if a gambler who has the same $10,000 gambles for above $5,000, and he loses all of them, the gambler won't be happy about his actions, and it might result in chasing of losses (which means he didn't gamble for fun).
I quite get the gist but you didn't cite the examples well. For correction's sake, the gambler who has $10,000 and gambled $1,000 out of it and the one who has the same amount but gambled $5,000 are taking too many risks and none of them will find it funny. The notion is about gambling 10% and 50% of your entire money, both are ridiculous, except that one is more biting than the other.
The $1,000 is not a small money and I am sure that the gambler will regret losing it because he might have spent that money on better things, what is fun about that? It's either you gamble for the money or the fun and if you opt for either of them you have to carefully define them to avoid later regret. If anyone would truly gamble for fun, it's better he uses a ridiculously low amount of money for it, that's what will not ruin the party.
You might have the $10,000 and start gambling with between $0.5 and $3, this is fun and will not affect you. But still, you should know when to quit the session because as little as the wagering amount is if repeated too many times can sum up to a big and painful amount.