It's an utter crock of shit that women will end up financially vulnerable if they are SAHMs. They haven't been 'financially vulnerable' for virtually half a fucking century. This is just a load of shite that some working mothers tell themselves, to make themselves feel better, because they HAVE to work, they feel guilty being away from their kids, and they see themselves as morally superior because they class themselves as independent, and are not 'kept by their man,' (stupid fucking saying that is!)
Many of these smug women who look down their nose at SAHM's would struggle if they split with their husband, and it makes me laugh that they think they will sail along beautifully - alone - whilst all the SAHMs will be crying, under a subway, in a cardboard box. Many SAHMs I know have done very nicely after splitting with their husband thanks very much!
Again, this is something working women tell themselves to make themselves feel better. 'Oh at least I am independent,' When the fact is, if she splits with her husband, she will be no better off than a SAHM who splits from hers. (She will be worse off probably!)
It may have been the case 70+ years ago, but these days SAHMs will NOT be any more vulnerable than working moms if the couple splits. And despite snarky comments about 'having to ask him for money,' many women who stay at home with their kids have plenty of access to the family finances, and indeed, in many cases, they deal with the finances, and the husbands don't even bother with it, they just leave it to their wife..
On the other hand, some women who work, don't get to go draw 'their' money out and spend it on goodies, (like some are making out!) because their husband has control. And even if he doesn't, all the money goes on bills and mortgage/rent, house repairs etc anyway. So this 'I have the joy of spending my OWN money how I see fit' is a load of crap.
It's a laughable myth that all SAHMs are sad little puppies waiting for a few pennies for a loaf of bread, from their high-earning hubby who is in full control of her and everything she does!
I worked for 30 years, (full time half of them, part time the other half,) in a high-paid government job, and when I went part time, (when I had our daughter,) not a week went by when I didn't get rude and snide and snotty remarks about 'only' working 22.5 hours. Jealousy it was. Pure jealousy. And projecting their insecurities onto me.
And at 48 I took early retirement, because I could. I have my own income, we have no mortgage, and DH still works, and we do very nicely thank you.
But even NOW, the amount of jealousy and bitterness that comes from some (many of my generation - 40 to 55 y.o,) knows no bounds. They cannot BEAR it that I don't work. 'Well surely you must miss it?' 'Do you think you will ever go back to work?' 'Don't you get bored?' 'Come on, you're waaaay too young to be retired!; 'Are you OK for money with only him working?' (Errr, I have my own income thanks..
AND 'my fave one.... 'what do you DO all day?'
Exactly what I like. I can get up at 7am and go for a long walk, or bike ride, or a horse-ride, or I can lie in til 11am and watch crappy tv til 5pm. Or maybe I will go to the beach! Or maybe I will take our daughter out shopping for the day, or meet a friend for coffee, and go to the flix.
Yeah there are some rude remarks made towards working women by SAHMs, but there are waaaaay more rude remarks aimed at SAHMs by working women.
As I said, it's jealousy. Can't bear it that they have to work. I mean not ALL working moms/working women are jealous of SAHMs of course, but the ones who make the snide remarks are.. (Eg I' would have no self respect if I didn't work,' 'what is this, the 1950's?' and 'are you OK having to ask him for money?') 
No SAHM that I know does that. It's not the 1950's after all! 
I am actually seriously wondering if what the OP said even happened, or if this is a thread set up to bash SAHMs. I mean all this 'why are women happy to be kept?' bollocks is doing my fucking head in. It's just as bad as other women saying 'how can you go out out to work and leave your children with a stranger? Don't you feel GUILTY?'
That is a nasty thing to say, but so is 'how can you be 'kept' by a man?' No-one is being KEPT! For fuck's sake grow up. It's a JOINT DECISION between the couple, for one parent to be the earner, while the other is the homemaker and raises the kids. And don't even TRY and suggest that men only go along with it because it's only WOMEN who want babies. I know more men who were desperate for a child than I do women who were, so that bullshit ain't gonna wash!