None of those examples exist primarily to aid criminals though, even if they can be used in that way.
* Tor & encrypted messengers: the whole "going dark" paranoia from mid-2010s
* Knives, guns, explosives: mass shootings and domestic terrorists; "nobody needs military style weapons"
* recreational drugs: see the War on Drugs which is really a war on poor non-White people
* cash: see the death of the €500 note
* masks: see the anti-mask laws intended to target the KKK
Note that I'm not claiming that society should never be able to regulate tools. Certainly I don't want the disturbed guy down the street making Ricin in his garage. We should keep in mind though that the tools themselves are value-neutral; it is the people who use them that give them a value.
This is not true of something like Tornado which exists primarily to launder dirty money, even if it has fringe legitimate use cases.
It's not paranoia if they really were out to get you (and largely succeeded, it seems)
I’d bet that there’s a chance a majority of users aren’t breaking local laws, at least if you exclude small scale tax evasion, but it takes an awful lot of people who care enough about privacy to pay extra for it to balance out the $450M USD-equivalent which just one North Korean group is alleged to have laundered. People who care about privacy will use it some of the time if they remember but someone with a lot of stolen money is going to use it every time and that will start to dominate the transaction volume, especially any time gas fees go up and people who don’t need to decide they don’t care that much.
Let's be honest with ourselves. Mixers are used primarily for crypto transaction laundering.
About as true a statement as Tor being primarily used for CSAM, and no-one actually caring about e2e encryption who isn't trying to hide from the law.
Pity the undesirable, lest one day ye be counted amongst them.
If you are trying to hide a purchase (with your own money) from your wife because you think she wouldn't approve, that's totally ethical (if a bit of a silly relationship tactic). Similar if you're trying to hide a donation to an unpopular politician or charity from your employer. If you're trying to hide a donation to a militant organization, it's much more ethically complex and depends on the goals and actions of the organization. If you're trying to hide the source of ill-gotten money, it's likely unethical.
Separately, while the tool might be "primarily" used for unethical things, that does not make the tool unethical itself. Again it is the actions of the users that determine this. Even if hypothetically 95% of Tor users are pedophiles and ransomware crackers, that does not invalidate the "legitimate" ethical use of the tool by the remaining 5%.
For example implementing KYC and AML processes.