Estimated annual costs of building a net-zero society are similar to the estimated annual costs of the damage from doing nothing. Both are, globally, in the trillions of dollars.
However, the two costs are not equivalent. Paying to develop more sustainable ways of doing things is like paying a mortgage; it’s money you pay out to have somewhere nice to live. Paying for climate damage is pure loss; it’s like setting fire to bank notes.
Furthermore, the costs of sustainable technologies (e.g. batteries and solar panels) are rapidly coming down whilst the costs of climate damage will only climb with increasing temperatures.
So, whilst the costs of doing something, or doing nothing, are about the same at the moment, they won’t stay that way.