Their reasearch: "If we lobby really hard, get someone's political career tied to the success of our project and sink enough public funds into this so backing out is no longer considered an option, we'll make tons of money. p=0.05 btw"

Their research includes producing the nuclear power plants on the UK's submarines btw:

https://www.rolls-royce.com/products-and-services/defence/su...

Why wouldn't you lobby to get public funds _and_ do something that can actually sell mass market?

Because one of those is difficult.

RR deciding to lobby in the UK for business where they have few competitors (versus in renewables where their competitive landscape is considerable and growing by the quarter) doesn't seem like an ROI I buy into, much as Phillip Morris' "scientific research" into the effects of smoking on lung cancer didn't seem altogether self-serving.

I think these projects are less about making money directly. Mostly these projects are only profitable/feasible with the help of lots of government funding. I assume they have secured some of that.

The reason that the British government is interested in subsidizing nuclear is that they want to maintain their nuclear capability and want to stay credible as a nuclear power. That, and the French are also investing. Either way, that makes it interesting for the likes of Rolls Royce to get involved. There's government money to be had. And maybe Rolls Royce stumbles on something useful; like a cost reduction that makes nuclear a bit less expensive. I wouldn't count on that happening quickly though or in any amounts that really matter.