(3) Bitcoin's only intrinsic value is its utility as a method of payment. Its value as an investment depends entirely on that utility.
No, this is not true. A significant portion of bitcoin value comes from its utility as a storage of value: an asset that is scarce, non-confiscatable, exceptionally carriable (cf. gold), pseudonymous, uncorrelated to any traditional asset, and more.
(The last one is in fact a defect.)
Yes they do.
No they don't.
Think again about the Pluto land example. With the premise of UN guarantee etc, it has all the qualities that you listed. Why wouldn't it be a good investment? The problem is not that a comet may dig a crater in your plot.
The problem is that its value is not pegged to anything. Therefore it may perfectly go from 1 M$ to 10$ at any time, without any reason.
That in fact is what has happened to Bitcoin in the last six months: its market price has changed drastically and unpredictably, because it is not supported ("yet", you may say) by its use as currency. The demand that lifted the price at the current 620$ was entirely speculative, and there is no argument that excludes it going to 400$ or 1200$ tomorrow. We have seen it reach both.
Or consider any altcoin, no matter how stupid. It may never be widely used as currency, but apart from that it has the same qualities that you listed above. If those qualities were enough, then any altcoin would be just as good an investment as bitcoin.
Not this BS again.
1oz gold is 1oz gold is 1oz gold. Its value is not pegged to anything.
For alt-coins, bitcoin is better than alt-coins because of its novelty. You may have 1000 bitcoin clones, but Bitcoin is always the FIRST successful cryptocurrency.