People into bodybuilding have been using whey protein for decades. There's not that many extra people into bodybuilding now to account for the extra demand.
There are orders of magnitude more people exercising at gyms with the specific goal of achieving some kind of desired body type, even if they aren't bodybuilders per se.
Theres definitely a much larger population who cares about 'macros' now vs just those specifically in the bodybuilding space. A very high percentage of people that workout regularly in any capacity supplement their protein. Whey protein is generally the most economical way of doing that.
