Well, you just said that's he's wrong. One "killer application" is that it's a "stable" store of value. Not perfectly stable, it can quickly fall by a factor of about 2, and if you buy in the worst bubble it might fall to a fourth of its value. That's decidedly less stable than Western currencies, but it's more stable than some others. And for many people Bitcoin is more accessible than the foreign exchange market. It also tends to rise in value over sufficiently long time scales.

The other use is providing online payments to people who aren't in the banking system. The banking system requires trust, and shuts untrustworthy people out - both at the level of individuals and entire regions. Bitcoin eliminates the need for trust (on the monetary layer) and can thus reach more people.

Both are great applications. They are largely irrelevant in the West because only a tiny fraction of us experience those problems, but that doesn't mean they don't exist elsewhere.