The definition is basically: the practice of women marrying up. So my guess is that people have used the best word they could find to define a similar situation for which there is no definition. BLM changed the definition of racism with ill intent. I don't see how using the word hypergamy to explain how women tend to seek the most resourceful provider possible to be an example of ill intent. MGTOW guys who hate women certainly put a negative spin on the word though. Languages and vocabulary are always changing.
In regards to your belief that women are marrying down with the intent of having the upper hand, well, I suppose some women are like that. My belief is that as more and more women become more independent and outearn men, they see a dwindling supply of attractive men. That is why marriage rates are so low, divorce rates so high, and a plethora of single mothers exists. And men who have been burned by this or cannot secure a suitable woman with whom they can create a family are so bitter for this reason.
I personally see Asian women being the ones who are closest to practicing hypergamy in the strict definition that you are referring to. When I was using online dating a few months ago, Asian women would try to screen me in the most impersonable way right up front. Many white women are like this too I suppose. I think women in general, regardless of race, just have the gene to be hypergamous if given the opportunity. It's just hardwired into their DNA.
