Not necessarily because they personally want to ride a motorbike - but as a matter of principle. That government should govern as little as possible, that the fewer laws there are the more freedom people have, and that if you're not harming others the government should get out of your way.
They would say if while riding a motorbike without a helmet you should crash and die that's tragic, but the price of freedom is that sometimes people will make bad decisions.
I don't agree with this personally - but I can understand why American lawmakers would have a bias towards inaction.
There are an infinite number of ways to kill yourself, degrade your health, or commit actions that lower your overall physical or financial fitness.
We can't put bubble wrap around all of it.
We evolved into this harsh physical world. We can be caring and educational and empathetic, but it's our universe to play in for a super short moment so long as we don't fuck it up for other people too.
A motorbiker who dies in a crash isn't around to tell us he's cool with it, and his distraught family often won't be cool with it. So the "yeah the consequences are fine" voice often won't get heard.
A motorbiker who gets left in a wheelchair might have a change of heart, and sue someone for compensation. Who wouldn't, if millions of dollars are on offer?
Drunk driving endangers other road users and I support it being illegal, but some might say a drunk driver hasn't harmed others until they've actually caused an accident. Once you start adding in statistical harms done to society as a whole, that opens up a big can of worms.
I feel that legalising the supply of all addictive drugs probably wouldn't be good public policy.
However, I'm in favour of beer, porn, gay rights and music with offensive lyrics under the principle that if you're not harming anyone the government should get off your back.
Of course some people, for political reasons, want to pretend that such choices don't exist and anybody who thinks they can have any control over their life is delusional. Rejecting such sentiments is the healthy choice.
The knock-on effect of these events in American communities must be horrific. How many victims who survive them directly or who lose their loved ones to them fall into deaths by despair or go on to live severely blunted lives that cause them to act out in ways that are detrimental to your society?
That's but a microcosm of the kind of stuff that Americans deal with that people in other countries don't. It isn't normal and it isn't something that your average citizen can just avoid by choosing better.
ETA: In the 25 years ending 2022, 122 people died in school shootings. That's 5 people per year. There are ~3000 homicides every year of Americans under age 20.
There's also a UN report which lifts up Sweden as an exception to the rule that violent crime is on the wane [2, page 119]: Sweden has experienced unprecedented levels of gang violence and firearm-related deaths in recent years ... Sweden had one of the highest levels of firearm-related deaths in a study over 20 European countries
[1] https://sv.wikipedia.org/wiki/Kriminalstatistik_i_Sverige#/m...
[2] https://www.unodc.org/documents/data-and-analysis/gsh/2023/G...
Obviously, this is a complexe social topic. To pretend to provide a panacea of all criminality generation all by oneself is asking too much for any individual.
[1] https://www.news.iastate.edu/news/2018/12/18/crimehistory [2] https://www.silive.com/news/2023/04/nyc-shoplifting-report-s...
Here (USA) billionaires microdose acid and take molly in the desert. The culture around drugs is entirely different.
While Singapore has a lot of things going for it I wouldn't really consider it more free than Norway, even if drug consumption is substantially restricted there.
You could do the comparison using other crimes instead, but bodies are a more concrete metric. By the way, it's not just Singapore.