I wonder if the people has believed the 5g conspiracy fantasies feel remotely foolish

They don't. In fact, they don't believe they were wrong. They've cherry-picked their array of half-truths and benign or unprovable conspiracy theories and have never reevaluated since. Or they've morphed their beliefs into cheap versions of the nonsense they once took as true.

Even with the covid vaccine conspiracy theories. They were saying that everyone who took the vaccine would die.

To maintain their "rightness", when questioned, they will point to the statistics of the non-zero number of people who did die from taking the vaccine.

When pointed out that the actual number is much closer to 0 than the 100% that they had been saying in 2021 or so, they will argue that there's a coverup or something. Or that they didn't literally mean 100% of people.

Obviously they meant whatever would make them right. Some people can hardly fathom the fact that they believed something to be incorrect.

I mean, people still believe the earth is flat, ffs.