Gas has low capital cost but relatively high fuel cost, especially outside the US. For most fusion designs (possibly excluding NIF), the fuel cost is insignificant.
Also of course we might want to consider the carbon emissions of gas plants.
That is what I mean. Some people are imagining the capital costs of a natural gas plant with the fuel and environmental costs being almost nothing. There is absolutely nothing to suggest that a fusion plant would cost anything less than a fission plant at this point.
Also of course we might want to consider the carbon emissions of gas plants.