I'm not necessarily saying we need to immediately stop all fossil fuel usage. Its going to take a little time for our technology and economy to adapt to changes. But in the long run, we will be better off if we limit the use of fossil fuels than if we don't.
I am fine with investing in technology that is economical and actually replaces what we already have. The issue is there are few options available to use and some of those (nuclear) are not politically viable. The net result is adaptation is not a choice: it is the only option we have. My main concern about the mitigation or nothing activists is they are pushing govt to make promises that we can't keep based on delusional fantasies. This diverts resources from spending on things that might actually help and, in the worse case, damage our economy in ways that leave us less able to adapt as needed.
CO2 mitigation causes real harm if it means future adaption is harder.