The Packs...

I know "the odds of any individual box containing a Revan's Mask is still 1/100" just having more boxes gives you more 1/100 chances increasing the odds that one of those boxes will contain what you are looking for (as explained in the maths section above).

Um, no.

One Million Boxes X 1/100 Chance = 1,000,000/100,000,000 = 0.01%

It does not matter how many boxes you open up.
Your chance of receiving a rare item is as identical on the first box as it will be on box ten-thousand.

This is the fallacy of a gambler and the reason why Bioware is never going to let these packs go...

To be honest, the only thing worth doing when a pack update comes out is wait a few days until the GTN gets flooded with the items, then you can just go around buying the weapons and armor for around 50-100k and the pets for the same. You'll still have to shell out over 1mill at least for the rarer mounts but it's cheaper this way overall considering the old pack items can still turn up in the new packs, even less chance of a rare.

This probably keeping the gold sellers in a tidy business.

At $20-$30 for a million credits? You can spend $20 on Cartel Coins and make FAR more than a million credits with selling the packs. Anyone dumb enough to buy TOR credits from farmers would be dumb enough to regardless of the situation.

To be honest, the only thing worth doing when a pack update comes out is wait a few days until the GTN gets flooded with the items, then you can just go around buying the weapons and armor for around 50-100k and the pets for the same. You'll still have to shell out over 1mill at least for the rarer mounts but it's cheaper this way overall considering the old pack items can still turn up in the new packs, even less chance of a rare.

What server are you on? Some pieces may go as low as 5k (the common mounts and armor pieces like boots), only a few of the weapons go below 100k (actually, it's only the sniper guns that go cheap, I guess the TAC hud is a bit too TACky). Half the weapons still sell easily near 200k, even the Black Nebula Blaster from the first pack goes around that rate here. The Phantom chestpiece goes between 300 and 400k, as does the Lhoosan Manta. The really rare things, like thrones, meditation chairs, Revan/Nihilus/Phantom mask and the rarest of pets range from 2 to 4 million.

Still, I wouldn't buy packs to earn credits. There are some really cheap unlocks I'd pick for that, which generate an exchangerate a bit higher than 1:1000.
And from what I've seen, opening 3 packs isn't a very reliable method of aquiring any of the special items. You might get one of the uncommon mounts or something like that, but it might as well result in 2 tossballs and a bunch of banners. The 70k credits was actually a pretty lucky draw for OP, the total value of those three packs could've been much, much lower, like barely 3k, which is NOT an exceptionally low result.