Taught Master’s and second entry degrees like MDs and JDs are bad for different reasons. The first enable credentialism, which should be discouraged which tax does. Second entry degrees are just bad. Make people spend seven/eight years of their life in college instead of the three/five/six that’s common outside the US and wannabe colonies like Canada or South Korea.
Mountain climbing results in dead people and large hospital expenses and mountain rescue teams rescuing people.
Most alcohol is drunk by alcoholics. Most marijuana is ingested by people who spend over three hours a day stoned. Both of those are bad and should be discouraged. Alcohol probably causes more economic damage than every illegal drug combined.
"Bad" isn't enough, needs to be external to the participants (hence the term externality).
As you point out, there are externalities here of sorts. Government healthcare is often considered bad by libertarians as it seemingly gives the government the right to control people's lives (e.g. oblige they do exercise or not eat red meat or not have unprotected anal sex or whatever) in the name of reducing the costs on the healthcare system.
That said, if an opt-out was allowed to be used by the mountain climber or couch potato or go karter or bare backer that states the government has no obligation to help in the event of a bad outcome caused by their activities then the "externalility" disappears.
This is noteably NOT the case with the more classic examples of externalities such as pollution. Doesn't matter how many waivers the polluter signs, other people still get lung cancer.
Mountain climbing results in dead people and large hospital expenses and mountain rescue teams rescuing people.
Most alcohol is drunk by alcoholics. Most marijuana is ingested by people who spend over three hours a day stoned. Both of those are bad and should be discouraged. Alcohol probably causes more economic damage than every illegal drug combined.