The idea isn't to hold out forever, just long enough to let the innovation curve flatten somewhat. Remember, "from $4.00 a watt to $1.25 in three years". Buying now means you're locking yourself into a given year's technology and pricing for the next 30 years, exactly when the price per watt is dropping insanely.
That reminds the "rifle nightmare" of the Russian Defense Ministry (1860s-1870s). Every new rifle system accepted was entirely obsolete the next year. By the time of Russo-Turkish war, the army had 10-20 completely different rifle systems in use.
That was over in 1891 when Mosin-Nagant was introduced. That one was in use for 60 years, including both World Wars. (Germans had highly similar Mauser rifles.)
When the paradigm is changing, investing is risky.
