“its just one glass of wine” can be equally said with “its just a small bump of coke” or “its just half an oxy”

No, not really. Each person is different, set and setting are different, circumstances can be different.

In any case that silly graph you posted was made by:

“opinions and judgment of 15 researchers, doctors, and a journalist. These opinions were exchanged and discussed during a 1-day workshop” … “given that it has no input other than the experience and knowledge of the participants involved, it is unlikely to be unbiased”

Although to be fair, the group that made that study now is advocating ways to get medical cannabis and psychedelics to people, which is more or less in line with the graph I suppose.