I swear, I saw an episode once where the leader uncovered the final DD on the final clue of the second round. They were leading by like $2000 (like 14,000 to 12,000). You already know what happened next: they bet $4000. WHY? Is an 18,000 vs 12,000 lead any safer than 14,000 to 12,000 in Final Jeopardy? Really?
Yep, he bet $4000, then whiffed on the answer. Now trailing $10,000 to $12,000 and gifting the lead to the challenger just as the round ended. He went into FJ in second place. Both him and the new leader got the FJ answer right, and he lost.
I've never seen a stupider move. Just bet $1, or 1000 if you have to. But seal the lead going into FJ. It irks me to even think about how dumb that is.