The real problem with Bitcoin is not, that
- in the financial sense its nothing like a currency, and more like playing lottery,
- it fosters illegal activities, like drug and weapons trade, tax evasions for the rich, etc.
but that
- it's doing an absurd amount of environmental damage.
It uses about 500.000x (yes, five-hundred-thousand times) more energy per dollar for every transaction, than credit card payments, and is already contributing to the global CO2 emissions as much as some smaller countries, despite only accounting for a marginal amount of financial transactions. And that this will only get worse with time, and the environmental damage will only increase as long as the system is kept running, and will exponentially get worse as long as the exchange rate is increasing and/or more and more entities will trade using it.
If for nothing else, for that (ie. the environmental damage done) alone Bitcoin should be banned and outlawed all over the world.