---snip---
If you can make these returns in 90 days then take your own money and become rich

Because we need more capital, and as you can see we have maximums in our plans, there are points where earning these ROI's become a lot harder, you cannot keep on going and going until you are rich that's not how trading, mining or any earning method works.
why do you need more capital. If you start with 1BTC you have about 467BTC in one year.
And of course it works like this. If you risk more in trading then you will gain more.
And especially if you buy more equipment for mining you gain more but mining might not be profitable like these rates at all...