One of the reasons that people don't want to take a card the first turn is because the first to turn in only gets 4 troops and the later you turn in, the more you get. Some people actually go so far as to not attack at all in order to get that 5th card that forces them to turn in later so they can get more troops when they do. While that makes sense, there's another way to look at it.
If you do go ahead and get that first card on the first turn and continue to get one each turn, you'll be turning in first and getting the measly 4 troops but when that last player, that 7th one, gets his fifth card and turns in for 20 (we do get 12 after 10 here and don't go straight to 15 from 10, right?), then if you continue to turn in first, although you'll get less than the others, you'll have less cards when that second round of turnins starts at 25 troops. And with fewer cards, you'll be a much less tempting target for elimination than the others.
I often turn in whenever possible instead of waiting just so I won't tempt anyone to eliminate me. It's the very strong players with too many troops to kill who can afford to wait for that 5th card before turning in.