Something is valuable because someone else also believes it has value. Have you considered that people put their money in Bitcoin to avoid it being stolen by nefarious/oppressive governments or to hedge against inflation or as speculative investment that Bitcoin will offer additional use cases in the future? Those all seem like legitimate use cases to me.
I don't disagree that it's an underground economy, but that's only because it hasn't hit the mainstream. But being underground doesn't necessarily mean nefarious or illegal. Those bad actors definitely exist in the Bitcoin economy and all other economies. But without some data I'm having trouble coming around to the idea that the majority of Bitcoin is used for illegal purposes.
I have considered that. Nonetheless, the people who try the hardest to get money out of oppressive countries are typically the corrupt - they know that their rackets have an end date and they want an exit strategy when that happens. We shouldn't kid ourselves - this is who we are really helping here. It's the same people who buy luxury apartments in New York and London and leave them empty just in case.
I find it hard to believe that anything beyond a small minority of transactions are the "good kind of underground transaction".
I don't disagree that it's an underground economy, but that's only because it hasn't hit the mainstream. But being underground doesn't necessarily mean nefarious or illegal. Those bad actors definitely exist in the Bitcoin economy and all other economies. But without some data I'm having trouble coming around to the idea that the majority of Bitcoin is used for illegal purposes.