I wish I bought $100 worth on BTC when I first learned about it and it was about 10c.
Crypto can be currency, commodity or property depending on its purpose and how regulators look at it.
There are many 'get rich fast' crypto projects practicing 'pump and dump' and there are many legit ones that have purpose.
Benefits of 'proper' crypto are in their portability, low storage cost and inability to fake it as well as fast and cheap transfers.
Unlike crypto, digital currency which govs will be mandating on us soon can be 'printed' and made with expiry date.
As far as illegal use, cash is still king in illegal use, anything can be used with illegal intent, even exchanging labor for goods can be illegal.