That's why they were prominent!
But they also had to correctly pick out the one which was the revolution - every such scientist faces tons of ideas and hypotheses to consider. Is your hypothesis here a kind of regression to the mean: all scientists are equally vulnerable to holding crankery?
Essentially, yes. They just happened to have had a string of sixes when they threw the dice, culminating in prominence. If you suppose that the crank-susceptible scientists significantly outnumber the crank-immune, you get predictions which resemble our observations that many prominent scientists are susceptible to crank.
Where by crank-susceptible I mean, approximately, susceptible to infection by crank...
Freeman Dyson writes in the New York Review of Books about people who took up the crackpot offer. Not just complete cranks, but eminent scientists such as Eddington who got into crankery in their later years.
New thing I learnt: Dyson was not only a good friend of Immanuel Velikovsky, but considers him a greatly underappreciated poet.