Lower the minimum investment so small players can try and invest on your site.
So not true. 10$ isnt so big investment.
In all plans - Principal included.
So if its not so big (and is not btw), why dont you make a giveaway?
With no guarranties for returning our money back, no facts that you are not a scammer or be one some time in the future, even 1 satoshi is too much...