How are monopolies dealt with under a Bitcoin standard?

Title says it all. Assuming that under a Bitcoin standard, the role of government in the economy is minimized because they have no power over issuing money. How would monopolies be dealt with? I have heard the argument that ‘if a company overcharges for a product, it opens the door for competition’, but what happens if companies can prevent competition at all? The two ways I think this could happen are:

1. You have a large stake in the vertical of the supply chain. Let’s say you make microchips and you own stake in the mining company, shipping company, and manufacturing company to ensure you get the lowest cost basis to produce your product. How does a new player in the market join if this example company decides to raise prices?

2. The Walmart strategy: you open stores in new areas and specifically lower your prices to take a loss on your store. Since mom and pop stores can’t compete with your prices over a long period of time, they go bankrupt from loss of revenue. Once the competition is gone, Walmart raises prices.

I don’t know how you can prevent this under BTC standard. The only case I have heard is that it is governments role to prevent it which is counter-intuitive. Any thoughts? Thanks