Let's say that fusion power is 30 years away - how much should you NOT do in other areas while waiting?

And if the cost of a fusion power plant is so high that you have to build continental-size reactors, what will then happen with the development countries? Will they also manage to invest and build a $1000 billion reactor?

And if we do get a continental-size reactor - how fun would it be for a terrorist to try to kill off the reactor, resulting in a huge lack of power for 300-500 million people?

Third thing - what is non-polluting electricity? If you are producing the electricity from deuterium or tritium, you are still part of the global warming. You want to make good use of the heat that the sun is already radiating (which you are with solar panels, hydropower plants etc).

As I said - it normally best to cherry-pick and implement cheap solutions with great potential first, and then slowly ramp up the more expensive solutions. And it is a known fact that it is very expensive to try to reach the technological limits. Counter-productive for a company to invest too much into reducing polution when the technology isn't mature enough. On the other hand - very good to be at the forefront with research, to get market shares when selling the new technology. And selling identical scrubbers to 100,000 factories makes the technology affordable, while at the same time letting the people who sells the scrubber make a lot of money.