I was just talking about this topic with a friend. "In criminal law, a conspiracy is an agreement between two or more persons to commit a crime at some time in the future. "
My take is that what has been mainstreamed is exactly the most extreme crazy conspiracies (lizard people from the planet Sirius (from V), eating baby brains to be immortal, etc etc) and that is actually encouraged. Its encouraged because it inoculates people against the word "conspiracy" so they are subconsciously less likely to believe all the very real, very mundane conspiracies that regularly go on and rarely get the damnation they deserve. The word itself "conspiracy theorist" has been codified to not actually mean what its etymology is anymore.
Many very real conspiracies went into the chain of events causing the financial crisis - actually many financial crisis are caused by literal conspiracies motivated solely by greed. Trump's finances and those of many real estate developers at that level are riddled with criminal conspiracy. The California energy deregulation was a massive conspiracy from entities like Enron. The Iran-Contra Scandal was a massive, insane conspiracy that still has not received the weight of scrutiny it deserves historically. In Italy you have P2/Propaganda Due conspiracy that reached throughout the power elites in Italy. The tobacco companies hiding and lying about health negatives of smoking was a massive conspiracy. Companies like Halliburton and other defense contractors committing conspiracy via False Claims Act violations that never get covered by corporate media. And that's just the major stuff that everyone knows about but rarely actually realize are massive conspiracies. You have documented human rights violation conspiracies from Western governments, particularly the CIA, you have all kinds of financial conspiracies that most people get too bored to conceptualize (without adding some lizard people) and you have governments like Saudi Arabia conducting assassinations in broad daylight and then having the gall to try to gaslight the entire world about it. And even though all of us know how shady the Khashoggi incident was compare how little that conspiracy was ever covered in world media because of how rich and powerful on the world stage MbS has become - the media of both parties talk more about Trump's tweets than this conspiracy the Saudi Royal government tried to pull in front of the damn world.
I feel great ontological sadness the instant people say "conspiracy" these days, even without constructing the loaded phrase by adding theorist, and the average person tends to tune out with lizard people thoughts instead of instantly thinking about the very real conspiracies of the tobacco companies, Iran-Contra and the Saudi's brazen conspiracy to murder Khashoggi and gaslight us all about it.
Conspiracies are very real and happen at every shady level of power.