The current 1990s-ish base-rate for ever taking psychedelics is ~10% of the population; the richer and more educated, IIRC, correlate with more drug use; the article is implied to be ~1989 in the PDF, and everyone she talked to would be at least 20 years old, putting their birth back in the 1960s at a minimum. What the Dormouse Said documented quite a number of interconnections between computing and psychedelics and hippies, so a large fraction is not implausible.

On the other hand, this reasoning sounds more consistent with, say, a third or a half, not 100% - 100% for both taking psychedelics and considering it important to one's work (and honestly saying so!) sounds implausibly high. My guess is some sort of sampling bias or maybe the journalist is overstating things; maybe word got around about her obsession with psychedelics and all the acidheads made a point of talking to her? We'll never know.