So your story is that when all other prices happen to go up, lots of greedy companies conspire to up their prices. But why do the initial prices start going up to kick this off? Cosmic coincidence? Or is it conspiracy embedded in conspiracy?
In macroeconomics, the motivations of individual firms don’t matter, or at least we just assume all firm behave as self-interestedly as they can get away with. This was as true in the 2010s, when inflation was low, as today when inflation is high. What matters are things like fiscal policy, monetary policy, inflation expectations, etc. Not how greedy companies are – we can assume they always are greedy.