As I moved up the ladder I replaced a VP and took on his shares instead as an incentive. It was 1.5 million shares. One year I landed a couple huge deals for the company and brought in bonuses worth more than the strike price on all of that and almost bought them.
While I was thinking about it, the executive in charge of marketing and sales left and I ended up meeting him in a local parking lot to pick up his laptop and some other things. He handed me and envelope and told me to give it to the CEO and that it was confidential. Being curious I looked in the envelope anyways and it was around 4 million shares in stock certificates in the company. I have no idea why they were being transferred but I'm sure it was some contractual contingency to return the shares based on some trigger in his contract.
Being honest, I turned in the stock certificates as instructed, but decided that something felt "off" and I chose not to execute on purchase of my options.
Over the next 12 months we tried to exit at a $25m valuation (which would have made me on paper at least a small time millionaire), failed to find a buyer, the CEO left, I became President of the company with the task to shut it down rendering my options worthless anyways.
In exchange for sticking it out and helping shut the company down, I left with a very nice parting bonus and a promise of strong reference from our VCs as a former corporate officer which helped me get my next position with another startup (which ended in disaster but that's a different story). All that was worth well more than my options in the end so I guess it was worth it?