Bitcoin as the main currency and doge as the alternative currency. Doge is the best coin for gambling because the fee is low and the confirmation speed is fast.
I am unable to understand that why people are wasting their bitcoins in gambling because gambling is riskier than other aspects in which one can easily invest these bitcoins and can get huge profits from it. I think if you have a huge craze of gambling, then you should better go to real casinos and spend your real life currency to gamble.
Anonymity is a huge part of it. People want to gamble online anonymously, and with currencies like Bitcoin (with the right precautions like blending, etc), this is possible, and there's another good point in the post you just quoted- quick transfer speeds. The same can't be said about fiat currency and bank transfers, etc. People are free to do what they enjoy, and just like with many modes of leisure (of which gambling is one), money's sometime spent that can be invested for profits, for example. Not every dollar you have has to be used towards making more money. There are very good reasons behind people gambling with cryptocurrency; don't say something's ridiculous if you don't understand it yourself.