The point I was making is that everyone's money that is used to buy the lottery tickets, goes into a pension fund, no matter how many people buy the lottery tickets. The number of tickets bought are capped at 3,000 baht per person each month, for obvious reasons.
However, whilst the 15 million baht in prizes might be much smaller than the total amount spent on the lottery tickets, that 15 million has to be paid for by the government, including the costs of operating the lottery program and paying the vendors.
A search on the internet reveals that the normal Thai lottery system pays 60% of the total sales revenue in prizes, and the remaining 40% is used to cover administrative costs and fund social programs.
It would appear that this new lottery system will pay 100% of total sales revenue to fund social programs, that is, the pension fund. All administrative costs and prizes will be an additional cost to the government, or a government subsidy, presumably paid for by additional taxes, or additional government debt.