A perspective from an economist
Secondary markets like the current IOTA/BTC market are essential to the primary market of the ICO. If there was no secondary market, the primary market would struggle. Imagine an ICO where investors know they will later not be able to sell their shares.
This link between primary and secondary market is not binary -- linked or not linked -- but instead very gradual: the more liquid a secondary market (and/or the higher the price), the better for for the primary market. If you think of the ICO as the initial primary market and today's market as the secondary market: without the expectation of the market today at the time of the ICO, the initial ICO market would not have existed (are much less of it).
In the nex step, you can think of today's market as the primary market and tomorrow's market as the secondary market. The logic is the same: the more liquid we expect the future market to be, the better for today's market (--> higher price today). This link is present from today to the (infinite) future.
The main lesson here is: any investor at any time always adds value to a project. Investors play an essential role for crypto projects in general, invluding IOTA. Of course, the coding is much more important. But the code would never come to its full potetnial wthout investors. Investors provide the financial incentive for all the devs in a project. Granted, there are incentives at work other than the financial one. But the financial incentive is rather important: after all, people have to eat from time to time.
Investors and developers live in a symbiosis.
Your logic is correct, but the company behind IOTA sold 'software', so the value of the token is not relevant to them. The metric to ultimately judge their performance is nodes in the field, not token value. As long as they're consistent I think they can continue to tell speculators to 'fuck off' (i.e. they can't claim credit for any x20 returns but can dismiss investor concerns about exchange listings today etc). David has chosen to reject the relevance of your analysis to IOTA, and as long as he doesn't claim credit for later secondary market values he's being consistent.
Despite agreeing with the validity of your economic explanation, with IOTA I am now using node numbers as the barometer to measure the success of this project. I changed my opinion from the start.
edit: I think a better analogy to use with IOTA is that of a creative pursuits like music, art, writing etc The sincere artist always prefers to measure success using the metric of 'users' or 'consumers' or 'viewers' of their work, the financial metrics of success (i.e sales) is an emergent phenomenon arising from the number of users/viewers/readers etc. Any artist who focuses on the financial metric first will generally produce bad art, but the ones who focus on reaching the widest audience as their goal will generally make better art, and as a side-effect, sometimes make money despite that not being their primary concern, or for some, not a concern at all. Any artist who tells you they're 'good' because they sold a lot of 'units' and made millions for their backers isn't a true artist though, are they! You can't have it both ways.