No, the massive growth is from podcasters telling them to do it, not because they're seeing results. They sound disgruntled every time I come across their videos online, except the ones who truly went into these relationships with a genuine desire for commitment, which isn't the case with most passport bros.
And about these other women being comparatively affordable that is true, but it doesn't last long. Men from my country who live abroad and come to take wives from home constantly nag about how women change or become reaching like their western counterparts once they're abroad. Feminists at home make it a point to school women on what are their rights and possibilities abroad and so, alot of that naivete sheds off quickly. Last year I met a man from my country who lives in the US and he was talking about signing a prenup with the lady hé was engaged to at the time. She's also from my country. That concept is unheard of. We simply do not do it at all, but he thought to be careful because according to him, well, just in case she comes to the US and goes rogue on him. We shouldn't underestimate the power of social media. And so, just as passport bros as a trend saw a rise because of red pill podcasters and Andrew Tate's promotions, women globally- even in these countries historically considered traditional are fast losing that mindset due to social media.

Then there's the other issue that even what the passport bro considers 'a successful venture' is really just the woman's venture to climb the economic ladder and relocate through him. To the extent that she can get this, she will comply. Once married, if they come to the US, she is still exposed to the culture of the western women and the western women's freedom is very seducing especially if her man doesn't treat her right. In the end, she still gets a good bargain; dollars maybe, citizenship likely, access to live and work abroad certainly.