He bet the final perfectly.
Going in to Final, Emma had $26,600 and James had $23,400. The dude in 3rd had $11,000
Even with a correct answer, the most James could end up with was $46,800. With the lead, Emma needed to bet $20,201 to make sure she could "freeze out" James with a final total of $46,801 should she answer correctly.
So knowing that Emma would bet that amount to cover herself, James only had to worry about the 3rd place guy. He needed to make sure that with a wrong answer he didn't fall below $22,000. That's why he only wagered $1,399. ($23,400 - $1,399 = $22,001)
So if Emma and James had both answered incorrectly, James would have won even if the 3rd place guy doubled up. That was the reason for the low wager. He was effectively taking the 3rd place guy out of the game.
As it ended up, both James and Emma answered correctly and Emma ended up with $46,801. Even if James had bet it all, he would have ended up with a 2nd place finish at $46,800
Only the winner keeps their final total. 2nd place wins $2000; 3rd place gets $1000.
James hedged his bet perfectly to give himself the greatest chance to win.