Some have argued that monopolists dominate the global market, and that is what is driving inflation (the aforementioned Richard Wolff has advanced this argument as well, as has the Biden Administration).
At first glance, this argument seems to make economic sense as monopolies charge a relatively high price and earn extra-normal profits. But the "monopolists are causing inflation" story suffers from a major problem: it represents a fundamental misunderstanding of the monopoly model.
Firstly, the monopolist firms maximizes profits where marginal revenue = marginal cost, and then charging the highest price the market will bear. The monopolist pricing will tend to be higher than the perfectly competitive market price.* Thus, there seems to be initial support for the "monopolists cause high prices" story.
But wait! We have a problem. The monopoly model tells us why prices are at a certain level relative to a counterfactual. But it does not tell us whether or not prices are rising or falling! Inflation is a general rise in prices. The monopolist model merely gives us a level. It is like saying that the water level in the pool is rising because the current level is 6ft. Again, to shift prices, we need a shift either in the firm's costs, consumer demand, or some combination thereof.
*It's worth noting that it is not always the case that monopoly pricing is higher than perfectly competitive. If there are single-firm economies of scale in the market, the monopoly price can actually be lower!
Unless we want to assume a single firm produces all goods and services within a country, the most a firm can do (assuming they're a monopolist) is increase the price in their industry. Thus, they can only influence relative prices, not the absolute price level in the economy as a whole.
Thus, in order for the "profit motive causes inflation" story to hold, we'd have to assume that all firms in all industries decided to raise prices at the same time. Even if we want to assume (unrealistically) that each unique industry in the United States has 1 dominant monopolist firm, that would mean there would need to be coordination and enforcement among hundreds, if not thousands, of unique industries within the US (I stopped counting unique NAICS codes at 100, and I was still in the second Super sector).