Trading 2nds for 1st and 3rds

[JDO]

I have been lurking around here off-and-on for awhile and I have read that you need to trade 2nds place finishes for 3rds and 1st. I am not sure what this means.
My ideas (all $10 buy-ins for sake of ease):

Is it purely a matter of EV?
Theoretically, averaged over time, you go into the money with the same number of chips as everyone else, and therefore have an equal chance at each place.
So 1/3*50+1/3*30+1/3*20=33.3333
which is less than 1/2*50+1/2*20=35
So 1sts and 3rds is a better money maker over time

Is it matter of hourly rate?
It takes the same amount of time to win $30 with 2nd place, as it does to win $50 with first. And less time to win $20 and 3rd place. So the least desirable place to finish may-be second (depending on how much longer it takes to win those extra $10).

Is it a matter of being more aggresive once you reach the money? The more aggresive player will win 1st place on a very small table more often. So he puts himself in riskier situations (meaning more 3rds when he loses, but more firsts when he wins.

Is it a combo of these three, or is there more to consider?

Is bubble play on a short stack a major consideration?

Thanks for any help.