Drug abuse is becoming more and more serious in my (made-up) country. A researcher team is now working on a new drug called Biological VR which has the following properties:
The drug is a psychoactive one, meaning that it changes brain functions. (Definition from Wikipedia)
The drug gives subjective changes to the intaker’s subjectivity, just like the illegal psychoactive drugs. The changes may be specified by the researchers, so a particular variant causing, e.g. the feeling of flying, the feeling of having sex, can be manufactured.
The side-effects of such a drug is substantially less serious. Therefore, while intakers may get headache, increased urination etc, they are not going to do something very harmful or dangerous. If you need a bottom line, something like the side effects of alcohol overdose should be appropriate. As a result, intaking and selling the drug should be legal around the world.
Addiction should not be serious, quitting is easy, and withdrawal symptoms can be easily tolerated. So intakers do not have to rely on constant intakes of the drug in order to live normally. Again, if you need a cutoff, caffeine will be an appropriate one.
The effects of the drug are non-lasting. In other words, the effects should not last longer than, say, 24 hours.
The researcher team wants to produce such kind of drug and sells it under an affordable price in order to deal with problems related to drug abuse. What are the potential difficulties for the researchers to do so?