Not everything is about economics, otherwise we probably wouldn't be talking about renewables at all.

Taking the long term impact of coal, gas and oil on our climate and nature into account, renewables are cheaper. The cost of destroyed infrastructure through (ever more likely) extreme weather events alone is immense and often not taken into account, not to mention the impact on food.

The amount of money countries have is limited. If the goal is to replace coal, gas and oil as quickly as possible it's more efficient to use cheaper technology.

As for "free energy", no energy is free.

Yes, my point was about already built solar and wind turbines, that lose money the moment they are not running. The same is true for a powered down nuclear reactor, as the fuel isn't the expensive part of the operation.
My point is that technology that is expensive even if not curently in use, does not make for good backup power. This makes renewables and nuclear not a good combination, as it's quite expensive.

Biomass isn't practical as it releases far too much emissions to be worth it, you almost might as well use gas.

Yes, biogass is only an option as an addition and shouldn't be used continuously (for backup power it should be fine).

This is especially true for Thorium technology or actinide burners. Actinide burners literally reuse nuclear waste.

Those are future technologies never used commercially (if at all). Thorium reactors are not even in the testing stage yet, it's even worse if you look at acinide burners. I'd like to switch to low emission energy now, not in a few decades.