Women have different hobbies, or indeed careers, than men. Not much competition in the market for manicure salons, for example (I'm aware of Phorest).

The women I know tend to have different creatives hobbies than men's creative hobbies (think crocheting vs woodworking). I'm willing to be there are more woodworking CAD programs than equivalent programs for crocheting in the market.

There are fishing lure design applications. Can you think of something similar for a more feminine hobby?

Off the top of my head: related to pilates, menstrual cycle tracking, childcare, crochet, knitting, home schooling, interior design, manicure, fashion, cooking. I would guess that any of these areas are less well-served by software than an equivalent sized market aimed at men.

It used to be that women had a lot less disposable income than men. But I don't think that is true in most western countries now.

BTW I'm not trying to be sexist or patronizing. I know that plenty of women are also into ju-jitsu, riding motorbikes, mountaineering etc. But some hobbies and careers clearly have a higher percentage of females.

I expect that markets for the elderly are also under served. Technical support might be a challenge though!