The same is true of any foreign currency. I could send $150 million in Russian rubles to my sister, and she wouldn't be able to do jack with it until she finds someone willing to give her dollars for it. With the amount of money involved, getting it all converted at once would be extremely difficult.
That's exactly the point. If you had $150 million in rubles, you could transfer it for only a nominal fee ($20 for my bank, although you can get a lot cheaper if you regularly did transfers like that) to any account in the world that could hold rubles. Exactly the same with bitcoin.
The only real cost in transferring sums of money is either extreme convenience, transferring to a country with an extremely poor banking service or exchanging currencies. None of which bitcoin solves yet.