LIAR GAME: REQUIEM

Hi everyone
I've got an inspiration for a new game as a fanfic (because I realise most fanfics of LG are about romance and not... a game round). So I wanted to present it here to see if it got any loopholes. Thank you!
Rules:
15 people, groups of 5.
1) each person given 1 card. Each card contains 5 million from the start.
2) each person must buy jewels. He will use the card each round to choose which box of jewels using a "computer". He can buy only 1 box per round. He can check how many jewels he have with the card. However, he does not know what other group member bought. At the 10th round, everyone's amount of jewels will be revealed. At the end of 11th, 12th, 13th, 14th, 15th round, you can trade and sell jewels, so it is possible to get 0 jewels.
3) There are 5 types of boxes available in infinite quantities. The \$100 thousand is the cheapest, \$500 thousand is the most expensive. Each jewel stands for \$10 000, but the boxes with the price might have less or more jewels than stated, the prices are rough estimates.
The estimated amount of jewels would be less or MORE, but they would be more than the next level.
Like for the 100,000 box: 0-19
200,000 box: 11-29
300,000 box: 21-39
400,000 box: 31-49
500,000 box: 41-59
4) each round, everyone must choose a box. Then, the total cost will be split among the members.
5) player with most number of jewels win and keeps his 5 million. Everyone must return 5 million. Group that wins get additional box of 50 jewels to be split as they wish. 10 people will be selected to pass, so besides the winning group & the winner (who might or might not be from the group), the rest will be selected based on how many jewels they have. AKA jewelsmoney if both have same value. If you don't pass, you don't proceed to the next game.

1. If everyone chose the 500,000 box, there will be TAXES of \$5 million to be split equally among 5 people, making it even more expensive than if just buying it alone.
2. If 4 people chose the 500,000 box, the person who chose the less expensive box will have to pay for EVERYONE but keeps his jewels, while everyone else gets their boxes as usual without paying.
3. If 3 people chose the 500,000 box, everyone pay equally, but the 2 people who buy the cheaper boxes will have no jewels-their jewels will be split among the other 3.
4. If the number of people buying 500,000 box is less than half of the group, AKA ⅖, then everyone pays equally and getting their own boxes. In other words, 2 people at any one time can buy the 500,000 box.
6. ASSUMING you used up all your money before game is over. If it's after the 10th round, you MUST sell your jewels in exchange for money. By now it will be obvious that people will buy. You will use the earned money to keep buying boxes. If you do not have enough money to buy the cheapest box every round before the 10th round, you will just get into debts and is FORBIDDEN to buy jewels from others and your card will be handed over to the designated captain. At the end, if you got 5 mil in jewels AND more than the rest and PASSED, your debt will pass to the next round. If not, your jewels is confiscated back as money, and you have to pay extra 5 mil as penalty, but you won't have to repay your EXACT debt which might be more or less.
Players:
Group Water: Akiyama Shinichi, Kanzaki Nao, Takeda Yukina, Sakiko, Tay Wan Ting
Group Earth: Yokoya Norihiko, Katsuragi Ryou, Shirokure Momoka, Fukunaga Yuuji, Lee
Group Air: Harimoto Takashi, Kei Kimura, Muraji, Sean, Kenneth

PS:

1. Communication is encouraged lol. Like Yokoya will obviously try to bribe people.
estimated amount of jewels would be less or MORE, but they would be more than the last level and less than the next level. The uncertainty of the jewel is what makes it interesting, heh.
Like for the 100,000 box: 1-19
200,000 box: 11-29
300,000 box: 21-39
400,000 box: 31-49
500,000 box: 41-59
So it's possible to get a windfall if you're damn lucky. There is no "minimum" jewels to pass the round, it depends on how many you have compared to others. As long as you voted and returned the 5 million (the amount can be in money and jewels, like \$3 million and 200 jewels, so only 10 rounds of buying 200,000 box would equal to that already).
3. In other words, money only matters until you get the 5 mil. So Nao's strategy won't work because she wants to ADVANCE to next round. so for the selfish group that buys the 500,000 each time, They will just continue to get debts which will be carried onto the next round, since the 5mil can come from money AND/OR jewels and the number of jewels is what's important.