Is there any historical precedent for a scenario like this?
There was a change in policy after Macri was elected, and the bondholders ended up getting paid $6.5 billion, but that was just a change in policy, not a response to any kind of threat.
https://www.nytimes.com/2016/04/25/business/dealbook/how-arg...
" Upon default, Argentina's bondholders sued to be repaid 100% of their bonds' face value.[6][20][21] Among the bondholders were vulture funds, who had speculatively acquired US$1.3 billion of the bonds' total value on the secondary market for cents on the dollar after the 2001 default.[5][22] Vulture funds also owned a large quantity of credit default swaps (CDS) against Argentine bonds. This created a further incentive to not only trigger a default against Argentina; but also to undermine the value of the bonds themselves, as the CDS would pay out at a higher rate if the defaulted bonds decline to extremely low values.[22] "
[1]: https://en.wikipedia.org/wiki/External_debt_of_Haiti#Indepen...
Besides, Venezuela's military is large enough to be a threat to Brazil and Colombia. All on wars haven't happened on South America for a long time, it is very unlikely that one will simply happen between not-too-asymmetrical powers.
At least here in Brazil, the government would fall if it decided to send people to die there.
What they've done is default on a bond payment. That doesn't mean that they have no money. The article has a graphic that says they have $9bn in reserves (though no details).
What it does mean is that, of the money they do have, they chose not to meet a financial obligation. There will likely be repercussions of this move but defaulting and being broke are different things.
Now, of all the people you probably want to make sure are paid are your military. Not so much to stop invasions but because the words "military" and "coup" have gone together often enough in history.
For example, how long does the rest of the world watch as Venezuela possibly descends into genocide and starvation? They're pretty close to starvation / famine now. Then if outside nations act, the ruling regime uses that as a tool to increase domestic patriotism to increase the power of said regime (if only temporarily). When Trump made the mistake of opening his mouth about Venezuela and the mess there, Maduro immediately utilized it for nationalistic purposes to give himself a small prop-up (Trump has lowered the volume since, on advice no doubt).
If Venezuela were to allow foreign nations in to help stabilize the country, what are the risks that those invited guests then plunder or annex (whether directly in a traditional sense, or by occupation & refusing to leave). From a very long historical perspective, that has to be taken seriously given the extraordinary energy resources of Venezuela. They've put themselves in a very precarious situation.
No private company wants to send in resources and investment just to see it nationalized. No government wants to buy oil with blood when they could get it more cheaply for cash on the open market. The most that would likely happen is covert support of rebels via third-party cutouts. For instance, the CIA (the US) might funnel resources through the existing US relationship with the Colombian national military, ostensibly to manage the FARC/ELN conflict and combat drug smuggling, but secretly also to smuggle supplies and dollars into Venezuela to support reformists.
https://www.theatlantic.com/international/archive/2017/05/ma...
https://panampost.com/orlando-avendano/2017/07/20/cuba-has-o...
Why would Brazil or Colombia want to be bogged down in Venezuela? If it becomes a failed state and a haven for attacks on neighbors, raids against the forces using as a haven are likely, but no one (except maybe the US, because that's kind of our M.O.) is likely try to invade and occupy, even to establish a new regime and then hopefully leave.
So much so they decided to base their entire planned economy on it, which didn’t exactly work out.
Almost like an economy that can adapt on its own might be a better idea, but I digress.
Works just fine in the US. Not like people are dying on the streets due to lack of healthcare or anything
Militaries don't really prevent invasions. Border security is about more than just securing from outside belligerence. It also does things like keeping fishermen from fishing in your waters, drug cartels from operating freely, and the like.