> If nobody else has to make efforts for sustainability, its a "pointless" investment

No. That is not true

* Unless you are evil using school yard excuses is off brand. You do the right thing

* Carbon free energy is cheaper to produce these days, so the premis is wrong

This politics. Burn the planet, it is what Trump would do

> * Carbon free energy is cheaper to produce these days, so the premis is wrong

If it's cheaper to produce, then there's no point in doing anything special, because it'll just take over via market forces. The "problem" with renewables is that the economics are fantastic in the marginal case, but if you need it to take over baseload when the sun is down, wind isn't blowing, etc., it's much more expensive because you need to build energy storage, which fossil fuel generators get for free. Going from 50% of power generation to 100% is going to be many multiples more expensive than 0% to 50%.

Until things like flow batteries become economical, in places without rivers you can dam for generation/pumped storage, it's probably not going to be feasible to go 0% carbon unless you just replace all of your baseload generation with nuclear or something.