Wow.  You are fortunate to have a wealthy father that is willing to give you this opportunity.

Yes it is risky.  Start-ups are risky investments too.  Having started a business that failed I know first hand how they can go.  Bitcoin has been much more profitable and we put WAY less money into it than we did our business.  Wish we had the money for BTC now, but oh well.  Life works out that way sometimes.

I think it is a gutsy move but all signs are pointing towards an amazing 2014.  My advice would be that as soon as the price that you paid for your BTC doubles, just pull out your initial investment and pay your dad back then you will have $1,000,000 in free BTC at that point!  Pretty cool!  

I would talk to an accountant too and figure out the best way to do that too.  There are some long term capital gain laws that carry into next year it appears that can put you at 0% if your annual income is in the lower brackets.  I am in no way qualified to give tax advice though so please consult a professional on this.  (Have to put a disclaimer here )