The ratio of legitimate to illegitimate use of traditional currencies is way different than the ratio for cryptocurrencies. Of course the total number is smaller, since the total number of cryptocurrency users in general is smaller.

The point is that there is massive legitimate use of traditional currencies, which makes them a benefit despite the illegitimate uses. The same is just not true for cryptocurrencies.

Also, traditional currencies have many, many safeguards against illegitimate use. Cryptocurrencies are specifically designed to prevent those safeguards.

There is a good reason that ransomware only took off once cryptocurrencies became available.