Private businesses engage in extremely risky enterprises everyday, it’s why things like explicit liability exist. The issue with something like this is their cost benefit analysis tells them that succeeding would create diminishing rates of return. Solving fusion reaction for the purposes of generating electricity eliminates a form of scarcity. Scarcity or manufactured scarcity is the only thing that enables corporations to continually increase profits.
Because the idea that there are vegans and vegetarians is an implied accusation of guilt to people that eat meat and animal products that are the direct result of animal suffering. Some people that don’t eat animal products might be militant or preachy, but I’ve never met one. In fact I have only ever met the inverse, people that constantly berate people for being vegan or vegetarian. Having been one myself, I can say that for me and people I know it is the same reason religious people hate atheists; their existence implies that people that eat meat are wrong and therefore bad people. Studies have confirmed this. Here is an article from the BBC that goes over some of the studies.