Did you trust the experts to have a solid national energy strategy too? Or did you trust the experts to have undertaken all the right flood defenses around Tewkesbury in 2007? Or did you trust the experts to have run Covid loans properly or PPE contracts? Or how about trusting the experts on the Piper Alpha oil rig disaster? Do you trust the experts doctors that make blunders in the NHS? Or how about the experts that built the Millennium Dome or any number of other national projects that went over budget?
Experts get things right the vast majority of the time, but they get things wrong too. All the examples above are where they got things wrong the wrong way, i.e bad things happened. But how many decisions get taken that may be wrong, but because no bad thing happened you never hear of it again. There is still a loss though in these cases because it creates inefficiency.
Oddly enough all of those examples you've made were decisions not made by experts but Politicians...Experts supply information and advice, but politicians make the decisions and provide the money in all those cases.
Experts have been saying our energy policy was bad for 30 years, and saying we needed more generating capacity and that nuclear was the only real option* if we didn't want fossil fuels, Politicians didn't want to pay for it**, or upset the nimby's even in areas where there was already an old nuclear plant that they were used to (and quite happy to take the money that was spent by the operators and staff at the plant in the local economy).
Experts have been warning about the flood risks and telling planning officials "this is a bad idea" about building on flood plains for decades, the planning officials when they do listen to the experts have tended to be overruled by the politicians...around my way the local planning officials listened to pretty much every utility and civil expert and refused planning permission to a large housing estate, only to be overruled by some twit in the government (often senior, often with no understanding about what they're actually doing as they don't even look at the evidence from the experts).
The Covid loans and PPE again were political decisions not experts, the government ignored the usual procurement process to basically throw money at donors who they knew, whilst the experts and experienced buyers and sellers couldn't get a call back, whilst the loans were done ignoring all of the normal safeguards including ones that would have just required a check against say HMRC and companies house....
It's odd how all your examples were basically experts not being listened to, or only a small number of optimistic predictions being listened to, rather then the larger number of less optimistic ones because it was politically better at the time..
It's also worth noting that for some of the flooding etc it's not that the experts were completely wrong, but that they underestimated the risk or other variables have changed, for example (and this is very important in the nuclear industry) they looked at what they thought was a 1 in 500 year risk and considered it not too bad, and then someone goes and builds upstream changing the risk level or you get a storm that's worse than has been seen along that stretch of river since proper records began and they find that they'd been overly optimistic (or that it turns out some old data was wrong).
*If you did some looking you'd see articles stating this from people in the industry and even some politicians going back to the 90's.
**For example they didn't want to guarantee a wholesale price of X in ten years time, when the price at the time was something like half that, completely ignoring the fact that there was a thing called inflation and much of our reliable generating capacity was due to shut down in the next few years...