Monopoly is Over-rated
When I was at the FTC, early in the Reagan administration, we had a test for whether an industry was a monopoly:
1. Rank the firms in the industry by size, from largest to smallest.
2. Now count the number of firms.
3. If the number is bigger than 1 it is NOT a monopoly.
Here is a slightly more sophisticated approach, but pretty much the same idea. Monopoly simply does not exist, outside of government action and a (very) few extraction industries such as diamonds.