All of the responses provided could potentially contribute to an invasive species outcompeting a native species, but the most significant factor is generally:
They have no predators, so they can spread rapidly.
This allows invasive species to establish larger populations and exploit resources more effectively than native species, leading to their dominance in the ecosystem.
However, the other factors like being introduced at high rates, using the same shelter or food resources can also play important roles in their ability to outcompete natives.