Lol, let's define monopoly first:
What is a 'Monopolistic Market'?
A monopolistic market is a theoretical construct in which only one company may offer products and services to the public. This is the opposite of a perfectly competitive market, in which an infinite number of firms operate. In a purely monopolistic model, the monopoly firm can restrict output, raise prices and enjoy super-normal profits in the long run.
It's not even monopoly. The cryptocurrency market is a free one, where everyone is free to choose which coins to use. Bitcoin is the largest because the majority gives it high regard, not because it tries to gobble up its smaller competitors -- something which monopolistic firms actually do. The market has actually been increasingly competitive if we use Bitcoin dominance as a "competitiveness" metric. Either way, you can't stop the best from being the most successful.
As we know other cryptocurrencies are copying the technology from BTC. So, BTC has the technology advantage that makes it great. So far, I find everybody just trying to copy the technology and strategy from BTC.