Duelbit becomes on of the most popular and used gambling site now so yeah small capital is enough to make way to win big.
You are right, in fact I also have a different opinion about the Duelbit gambling site, the only person who wants to join with small capital, easy for them for everyone can bring big profits, if they really have luck in gambling Duelbit.
Deposit $10-$50 you can follow the competency here:
https://bitcointalk.org/index.php?board=71.0, lucky ones can win many times the capital they deposited.
I also have a friend who told me the experience of betting on the Duelbit site, with a deposit of $50, one week can make $500, that's just by buying a Bonanza.
Yep, there are quite a lot of opportunities in Duelbits with minimal capital, even if you have a big chance to get big wins, I also have the same true story after I introduced duelbits to my friends so that it becomes addictive for him because the wins always come, whether it's always lucky or not. What is clear is that my friend really likes playing here.
Every time there is luck, any capital will definitely be big, at least we can go through the right stage, which means the same as your friend's story with $500 within a week.
So with minimal capital it can be played again but full of awareness.