Trading. Because the other option is too risky and not smart option to choose.
Trading is risky too, but i have control about my bitcoin not just 'give' my bitcoin to other site.
HYIP, Revshare, cloud mining, mlm, and gambling the best way to loose your bitcoin, not recomendeed.
Trading is good but the best way is to have some successful business related to bitcoin like exchanges and gambling sites, they are probably swimming in bitcoin.
Do you think that gaming sites provide the opportunity to earn bitcoin? I wonder whether you have the experience of playing games of chance, and how many have you managed to earn this way. If you honestly, I do not trust gambling, and I am sure that there may be more to lose than to earn.
It is very clear if you actually took the time to read my post, I was talking about owning a bitcoin related business, so of course you can make money with a gambling site if you are the owner or an investor.