The financial markets are uncertain and whenever anything significant happens that is adverse, the markets collapse. There are some major potential negative events in this country's financial future and it won't take many of them to kill the markets in which case the IPO market will decline faster and deeper than other markets. This situation is obvious and it is very much in the mind of any Engineers considering a change from Apple to some new company with a great idea and promises of an eventual IPO.
I mentioned IPO for completeness. The IPO was the keyword for the last two decades. Now the name of the game is being acquired by a big company. And that story is easier told and frankly, pretty easy to make happen relative to doing IPO. Look at the huge amounts of money thrown at the start-ups being acquired left and right by these larger companies.
Engineers at Apple are in a unique position to evaluate the company's future because they know what they are working on, they have some understanding of future development efforts and the company has a great history of producing things that work and that people want.
That amounts to absolutely nothing. No Apple employee sans the leadership group can predict the stock price in the slightest. I once took a Corporate VP job at a company that had just gone public a few months back. I took over from the founder and showed up to work with option prices of say, $24. Two weeks later an analyst says one of our larger customers is going to have trouble and that company's stock tanks and took us down with it. Next thing I know, our stock price is down to $16. Here I am at a new job and am facing options that are $8 under water! The CEO tells me to not worry. That the IPO generated enough cash that if the company vanished, the stock price would still be $12. So $16 is a bargain. Yeh, right. Stock proceeds to head down to $13. Then a corporate raider showed up to try to buy the company, shut it down and take the cash. So we hurry up and create a "poison pill" to avoid that. I left the company a year and half later and stock price was just $13 still. I had zero value for my options and hard work there while the founders bought $100K luxury cars and enjoyed their IPO.
Here I am as a director and officer of the above company and had no ability or knowledge to impact stock price. I knew everything, and thought it all pointed to better things but didn't happen. There is no way ordinary Apple engineers would have any remote idea or influence over stock price of a company like that. Indeed, that is the reason to leave a big company: in a start-up, you can easily influence and know what is going on in your company. Big fish in the small pond kind of thing.
Valley engineers are also accustomed to the wild IPO stories based on the senseless financial projections of companies with great ideas and they know that just a good idea coupled with extravagant promises isn't enough any more.
For every story of a start-up that went nowhere, there are 10 that did. It is all around you. With hundreds of companies at any one time going after this pot of gold, the success stories are there and huge motivator to jump ship. Yes, the one you choose might fail but so what? You try and try again and the third one would work. For me, the first start-up did it as we sold it to Microsoft.
You can also keep in mind that the existing otm options are unlikely to be the only options ever awarded to Apple employees. Many employees will welcome the low market prices of stock as an opportunity to receive fresh options at lower exercise prices. Goodness knows, Apple certainly has the financial ability/equity to award a lot more options whenever they wish.
That is the story that works for a bit: we went through that at Microsoft. You hang your hat on those "cheap options." A year later is the time of reckoning. If the stock has not gone up, that hope and prayer goes out the window. I just looked and in the last 12 months, Apple stock has gone *down* 32%. So all the options with that promise a year ago are now in a hole. Folks accept the story once, but not the second time.
I think you will find that there are many Apple employees who view the country's financial future with uncertainty, view the start ups and promises of IPOs with skepticism and do not feel this is the time to leave to join a new company that may or may not have a successful IPO.
As I said, if you are married, with huge mortgage, you may think that way. For majority of silicon valley engineers, that is not at all how they view the world. Working for a start-up is where it is at. They work for a public company as long as it is growing like mad. Anything other than that it means it is yesterday's news. There is a reason Google hires four star chefs to feed engineers free gourmet food. They have to do everything in their power to compete with appeal of start-ups.