[graemep]

Tobacco is legal because of large numbers of addicts which would create a huge market for illegal supplies. The UK plans to phase out tobacco by raising the age at which it can be legally bought every year.

In any case, this is whataboutery. There are lots of harmful things that adults are allowed, but lots that are banned for everyone. There are lots of things that cannot be sold without meeting safety standards (cars, electricals), or that are only sold subject strict controls (prescription drugs, guns). We do not allow adults to have whatever they want.