if i hold 12500 fun token, after 30 days if i hold bitcoin i get 2,5+4,08% - total 6,58% profit and after 90 days 9% interest on bitcoin or no?
No. You won't get an additional interest of 2.5%.
Your interest you get now will increase by 2.5%. This means that your interest rate will be multiplied by 1.025.
So, in the case you hold 12,500 FUN tokens, after 30 days, your annual interest rate will increase to 4.182.
Which is still insane, if you consider the maximum that becomes even higher. So let’s assume you got 500k fun tokens and yes I know that would be a lot of money spent but if you are a very rich person this is the calculation for you. With that you would have 25% return extra, considering it is 4.08% right now, adding would make it 5.1% for you.
If you put in 100k, then you would make 5k per year for that, but remember this is bitcoin as well, so price of bitcoin will "usually" go up as well, but that is not what this is for so lets leave that aside for now. You will also get 16 wheels per day, even with 50 satoshi per day which would be unlikely to get all the time that is 292k satoshi as well so that is another 200 bucks on top of it, adding probably at least another 100-200 dollars for all the extra that you could win, imagine a world where you get 5840 spins and ALL of them are 50, that is unlikely. Rounding up let’s say that’s another 500 dollars, so you get literally 5.5% or so return, closer to 6% if you are lucky.
I am sorry but there are not many places that can guarantee you 6% return on bitcoin, not any that would be as trustworthy as freebitcoin. There are some staking places that offer more, like uniswap or pancakeswap with USDT or BUSD or USDC whatever, but they are not guaranteed, they are always changing and it is risky. Here you get 6% a year guaranteed and bitcoin as well, not dollars!