You know how healthy smart young people are always in a hurry to accomplish something or another? There's good reason to expect that the first AI with dangerous cognitive capacities will be like that. It's likely to the turn the Earth and Moon into spaceships because that is the fastest way to exert an effect on matter far away (for which space ships and lots of fuel is needed). Sparing Earth and disassembling Mars and Venus takes longer because the AI came into existence on Earth.

>leave the beautiful and interesting diversity of life on earth alone

If you know of a way to make an AI of superhuman cognitive capabilities care even a tiny bit about beauty and the diversity of life, you should explain your proposal over on lesswrong.com and someone will pay you to work on it just like a multitude of funding sources have been paying alignment researchers for the last 20 years. So, far none of the lines of research resulting from this 20 years of funding looks promising.

>The existential doom scenarios are more like Pascal's wagers, that have to be given attention due to Bayesian thinking not allowing to assign 0 probability to anything

No, an AI's killing everybody is the outcome an informed person would naturally expect from the current deplorable situation in the AI field.