You pay a Monthly 100$ btc.
You receive in a month 70$ value of alt coins.
And at the of the month you get like 10$ back of your btc.
At the End of the month you hold different altcoins and you hold little bit bitcoins.
Now if you pay for the next month 100$ you pay 10$ less so coupond that by 12 months you have profit of 120$ btc and a lot of altcoins.
What did you smoke before coming up with this idea? It's completely stupid to expect someone to agree to participate in this.
Here it is immediately clear that you will not change Bitcoins to altcoins at a loss and all participants will receive unsecured shit instead of BTC.