Sorry, your argument is just silly. No one needs to buy an extra $90,000 in gear for a $10,000 camera just to shoot a project.
Sorry, that's non-sense. The Blackmagic URSA Mini Pro 12k Rig alone, like it's adverted on their site, comes very close to that, and that's without any special additional accessories. Talking of € here! A single Zeiss Supreme Lens cost 17k€, if you decide to get two or three it sums up quickly, and the full lens set is 90k€. Of course not always all lenses is needed, but 1-3 is very common, which probably is the reason why you even used two cameras, swapping takes time and breaks the workflow, and with two decent camera setups you pass that even easier.
Aside from the reality that most people would rent much (if not all) of this gear (certainly lenses), one could purchase everything that one would need for an outdoor shoot for an additional $15K shooting on sticks or $25,000 with a gimbal. Add a few thousand more for lights if one is shooting indoors.
Sounds like you're not talking for a company, these kind of things are written off and helps to lower the overall tax.
Renting is waste of money at long term, specially if the main business is film making.
Renting might worth for the occasional camera guy, or for the ones who "quickly" needs something because it's missing in his inventory, or can't put a higher amount of money on the table. Good Studios own these things.
Having shot a two day short film project with two cameras at 6K 60P in Blackmagic Raw just before the pandemic, I can tell you that I spent under $1,500 in gear rental and under $1,000 in additional gear purchased for the project. I would have shot at 12K but the Ursa Mini Pro 12K had not yet shipped.
Just because it suit your needs, doesn't mean it suit all needs, and since you're renting, you're out of the game anyway. Must have been a quick small project, few weeks or months of renting two cameras would have exceeded that sum by far, regardless of the currency.
Except that one typically purchases computers and one usually rents production gear.
Sorry, but i think there isn't any case studies out there showing that cameras is primary rented and not purchased.
Anyway, the ones who rents need to purchase.
In any case a 699€ M1 Mac does not even worth mentioning for 8k raw footage recording and editing.
It goes down like a toilet paper roll between all that higher priced equipments.