If playing the dice with bitcoins is against gambling laws, then so is playing monopoly with your family.
No for 3 reasons:
1) You are not playing monopoly on the internet.
2) You can not change monopoly money into a material amount of USD.
3) You are not playing monopoly as a business with the intent of making a USD profit.
If you analogy was correct then there would still be online poker in the US.
1) Yes I do sometimes.
2) Well yes you can, if you find someone stupid enough
3) I'm playing monopoly because I want more monopoly money.
What did the original miners pay for their bitcoins? Nothing, just like you get the monopoly money for nothing.