The Fear Factor
It's not so rare that a declarer is so uptight about the possibility of walking into the setting trick that he puts off chancing that play to the point where he must go down. The poster boy for that mind-set was a hand, laid out elsewhere, on which declarer had 12 top winners in a 7 no contract, and a 13th offered only on a finesse against a queen on a 5-card holding. I believe he held J low opposite A K 10. So this declarer simply put off that finesse, that sole chance outside of dropping a singleton or doubleton Q (and a singleton Q could have been guarded against back when he had many entries back and forth). He simple couldn't bring himself to take that finesse and came to trick 11 without having touched that suit, and now still unable to bear the thought that he'd take a losing finesse, he simply cashed his top two clubs and conceded the 13th trick to the Q -- on his left. I don't know what else you could call it but fear of going down inhibiting natural chances to the point of assuring that he'd go down.
To be sure, in referring to fear, I'm ratcheting up the analysis one level. If a declarer declines to take a very natural finesse against a queen with, say, 8 cards or fewer, that's a matter of public record. But if I say declarer feared the possibility of a losing finesse so much that he couldn't bear to risk that setting trick just yet, I'm presuming to know something of his mind-set. And naturally, one has to be careful about presuming to know another's mind set. So it behooves me to reflect carefully and consider other motivations. Nevertheless, I can only say that I find it a fairly common cause of going down that declarers certainly seem to be inhibited from a natural progression toward their contract and delay taking any risk not merely to the last possible moment, but beyond that moment till they're assured of going down.
So much so that I've listed this among the common reasons for a blown contract. Case 1 is as obvious as the no trump hand described above. It's inevitable that I'll be moving into more tenuous cases. But that's the way it certainly looks to me in all cases offered. Below are links to some examples: