Many people who have risked their money by placing it on Bitcoin likely had enough, and they risked the extra money that they had lying around. Why not place bets on something you think might be probable? Is there something morally wrong in making some extra buck? Is it morally superior just to keep your money lying on bank account or what?
I'm pretty sure these peeps who hang out at /r/buttcoin are going to work like regular people to get some fiat currency to their beloved government blessed bank accounts. So I guess they don't feel like they have enough.
To be honest I don't think the skeptical people thought bitcoin's success was probable and that's why they didn't bet on it. It's not really anything to do with them being content with what they have.
But it could be this too in some cases.
Some people do things unless they find a reason not to but so a skeptical person will only do things if they find a reason.
People who really feel they have enough might not see any reason to spend their time or effort placing bets, even on things they think are probable. But I don't think many people think that way.