In my opinion, after everyone gets their forked free coins, they will dump most of their bitcoins that they are buying right now. The price is currently pumped, because of the rumor of "free money" if you buy bitcoin now and wait for the fork. However, once they get it, people will want to sell their excess bitcoins, so you still have hope to buy them even cheaper than for what you had sold them. But the question is, do you really want to buy back all of them? I think it's worth to diversify, especially with a big money like yours.