There's angles to socialization. If a person with brain issues gets free doctor visits and a medicine, that is at cost to society.
If they are safe to be around and are able to hold a job or have children, then there's societal benefits gained. One could consider the treatment costs as investments.
If that person was untreated and they did something unpleasant or bad in public, or ended up in prison, that also has a cost to society though it might be more complex to quantify.
I think motorcyclists should pay more for health insurance insurance considering they will use it way more often no matter how well a driver they are, the risks are simply always present.
I don't see why not. Maybe no need to ban altogether, but a heavy tax on both might be useful. For motorbikes maybe just exclude accidents from coverage.
There's a long list of topics where this particular reasoning could draw a line somewhere. It is unfeasible and pointless to cover them all unless they are all banned or all allowed (this essentially is the current state +- AFAIK).
I'd say it is worth looking at redrawing that based on the maximum effect achieved. Drugs would be at the top of this list, followed by motor vehicle use and unhealthy foods. There is probably not enough justification to go beyond the 3.
If they are safe to be around and are able to hold a job or have children, then there's societal benefits gained. One could consider the treatment costs as investments.
If that person was untreated and they did something unpleasant or bad in public, or ended up in prison, that also has a cost to society though it might be more complex to quantify.