Then one could treat it like every other technology purchase ever: wait until you need it. That is, when the "costs of waiting" outweigh the benefits of waiting.
That way, you maximize your benefit. Once you need to buy, you have no other choice but to buy.
And then, you'll know you did the best you possibly could in your situation. Because one thing is virtually guaranteed: technology is going to get better.
True in many utilitarian cases, but I have never really needed a new car in the past decade, yet I think I've bought one approximately every year. Same applies to many technology purchases that include an emotional element, as opposed to solely rational.
And frankly, I don't think any premium vendor could survive solely on rational, utilitarian, need-this customers. They need and seek those emotional reactions, that desire to have their product, because there rarely is fully rational need that could justify those purchases.
And because it is an emotional and financially significant purchase, timing it right is already difficult as is, and even more so if the product is a constantly moving target. A product with several quarterly changes and a delivery time of 1-2 quarters is a difficult buy even for someone with fairly frequent car changes, let alone for someone who tries to time the best buy moment for a ten year car ownership.
Given what we know today, my seat-ventilating, spoiler-tucking, free-Supercharging, non-pack-interior-designed, Helix-sporting, 10k-cheaper Model X P100D AP2 certainly was a well timed purchase in the end, because now/soon none of those things are available any more, but it just illustrates what a terrible gamble buying a Tesla is these days. And soon something is bound to come along to obsolete even my well timed purchase.
Buying a usual car with annual or semi-annual upgrades and price-list changes is a lot less stressful from this perspective. Or buying an iPhone or a Samsung Galaxy, which is super easy compared to timing a Tesla buy. Basically you just decide do I need/want a new one this year, you get it after a short wait, and then there is basically a year before anything new appears.
With Tesla, they can add or take away basically anything at any given moment, and especially a few weeks into each quarter.