I don't necessarily agree: there are still SSPX chapels that are little more than a backroom or a garage, yet I've seen irreverent, rushed masses in exactly these locations. According to your theory, you'd expect it the other way around, but no. Also, one of the only Resistance priests in Germany, was - accidentally or not - head of the largest German priory of Rheinshausen (the German equivalent of St. Mary's). He spoke out and then got demoted to a smaller, unimportant congregation. So, money, fame or position do not necessarily corrupt good priests. Meanwhile, even hardcore monks like the Transalpine Redemptorists, originally created by some of Lefevbres first priests, fell even harder and went straight back to the Conciliar Church, despite not having great accomodations.
Why are some people more liberal / trusting Catholic authority and some are more conservative / distrusting authority? Why do some people "get it" what the fight is about and others don't? People might speculate it has to do with physicalites, i.e. if you're physically strong then you're going to automatically more steadfast - but I haven't observed that to be the case necessarily, these characters often fall into pride. Some speculate it's because of upbringing or it's about how much they had to fight to get to their baptism, i.e. converts are usually far more "on fire" than cradle Catholics. Some people seem to be more or less predisposed / inclined to liberalism, and truth is, I don't not know why. Probably it's because of how much they pray (and more about how fervently they pray and fast). Maybe it's a humble disposition of the heart?
Second, it also shouldn't always be like this, it's not the normal state of the Church to celebrate in garages. It may be true that the weak men -> hard times -> strong men -> good times cycle runs in the Church, but the Middle Ages had "good times" for hundreds of years. But we are not Protestants or iconoclasts who reject externalities, money or beautiful buildings in general. Maybe it was because life was harsh in general? If so, neither garage Masses nor opulent Masses will help to fix that as then the problem is modern life in general.
In general, people get the priests they deserve. The nithe cultural Sunday Catholics will get their nithe Novus Ordo bishop and then nithely fall into hell. The people who care about the smells and bells but not fighting for the doctrine will get their FSSP-TLM and suffer constant fear about having their indult Masses taken away. The people who understand Lefevbre but are more inclined towards liberalism will get the nithe SSPX. And the rest will go and seek out the garages / remaining monasteries themselves - no effort and no distance will be too great for them to seek out the Mass with a true, uncompromising priest.
I've recently thought about the verse "your body should be a temple". Most people nowadays, including the ones in the SSPX, are museums, not temples: maybe nice to look at, but without much love for the Eucharist inside. First of all, the people in the congregations have to be temples again, then the outside temple will come naturally.
I don't think a financial nuke in Menzingen will change peoples behaviour, it would also completely prevent converts from finding any close Mass at all. I am a recent (2023) convert and I personally went from being raised in a Baptist-ish dispensationalist family -> NO (for 3 months, I didn't know the TLM existed) -> SSPX -> Resistance. Without the SSPX existing at that time and place, without their websites listing their Mass locations, without their youth group welcoming me at my first Mass, I would not have found the faith and would likely still be Protestant. About half of my congregation are adult converts. Not everyone has the grace of growing up in a TradCath family, and even the families who were with the "old SSPX" fell asleep at the wheel and now go along with the nithe neo-SSPX, even after I warned them.
It's a great mystery why God picks some people over others.