Gambling and ponzi schemes are very risky it will reduces already hard earned Bitcoin.
If I have to choose between gambling and other investment sites then I would definitely try my luck on gambling as if I would be lucky on that particular day then I can make good sum of money in quick time but investing in online sites doesn't make any sense as the outcome from that would be surely zero which will result in loosing all our money so finally if you want to take risk of making quick bucks then its better to go for gambling.
Why do people like you only look at the positive aspects of gambling while the negative aspects are sitting on the same level. You can't just depend on the luck factor to constantly be with you, because at some point your luck will run out and you'll be losing hard. The far majority of the people lose against the house in the long term, that's a fact. Just don't get yourself involved in such practices. It's not worth it.
That's right its not worth to waste time and money on gambling as you will surely loose in long run and we have many other better ways of earning and growing our bitcoins so we should try to take help from them and trading is the most trusted way to grow your coins if you hold a good knowledge of it and trading will always have an upper hand in compare to other ways of growing bitcoins which are almost useless and not trustworthy.