If you have an issue with age gaps in relationships, that is entirely separate to a Gold Digger (GD) scenario. GD scenario’s are about one person duping another into a transactional relationship without their consent.
The central issue here is that the GD motives are financial while appearing to be romantic whereas the Financially Secure (FS) persons motives can be presumed to be at least as honestly romantic as anyone else’s. Dating a person because you find them attractive is kind of the point. Dating someone because you want access to their wealth and gain it via deception is immoral, irrespective of age (provided legal).
A GD is a predator, not a victim. S/he is knowingly engaging in an emotionally deceptive relationship which is actually transnational in nature. It seems to me like you want to find a reason to justify morally grey behaviour on the part of the woman simply because you disapprove of the age gap. But an age gap does not mean that the older persons motives aren’t pure. Life isn’t black and white and we have legal parameters in place to reduce exploitation (age of consent.) This doesn’t mean that exploitation cannot happen, of course it can, but you seem to want to justify the GD’s exploitation of the FS by victim blaming the FS because you don’t like the age gap. This is like saying a person was asking to be robbed because they left their window open on a hot day. Just because a persons behaviour doesn’t sit well with you doesn’t mean that they deserve to be punished via immoral or criminal behaviour.
FS’s have transparent motives. They are attracted to the person and wish to pursue a sexual &/or romantic relationship. This requires consent on the other persons part. Two consenting adults can do as they please irrespective on your views. GD’s are specifically deceitful and that shouldn’t require an explanation as to why it is wrong.
I think you should resolve your issues with age gaps in relationships between adults before you go in to bat for people doing immoral things simply because you think the other person is also doing something immoral. Two wrongs don’t make a right.