Is this hand indicitive of why I'm terrible at tournaments?

[Homebrew]

Hi all...my first post, so hope I get all the relevant info in. I've been playing the $3, $5, and $10 NL tourneys at Pokerstars and seem to just dwindle away about half way through. After reading these forums, I've been trying to play very tight until the blinds reach 25/50 or 50/100 and then start stealing and loosen up a little. Seems like the last several tournies I've gotten decent hands, gotten all my chips in, and then lost. I guess I'm trying to figure out how often do winning players actually put all their chips at risk in a tournament with 1000 to 2000 people? Only when they have the nuts? What's more important: pushing advantages or protecting chips.

Here's an example. This is from memory, but we're about 45 minutes in and the blinds are 50/100. I've recently been moved to this table but it doesn't seem an overly aggressive table. I have about 2200 in chips, about average. There are three limpers and I'm just off the button with J8 suited and I limp. I know I probably shouldn't even play this, but I decided to see the flop. The SB folds, and the BB checks. The flop is QJ8 rainbow. Checks around to the guy on my right (about 3500 in chips) who bets 300 into a 550 pot. I raise to 900, all fold, but the original bettor who goes all in. I call and he flips AQ. An Ace comes on the turn and I'm done.

Questions:

I know QJ and T9 are both distinct possibilities here. Should I be protecting my chips and try to see a cheap show down (or even fold), or should I be pushing two pair?

Go ahead and let me have it, I know I probably played this hand awful...but this brings up another question. If you knew 100% that you would have Jacks and eights against TPTK, would you put all your chips at risk this early?

Thanks much,
Jeff