I found it to be a good pedagogical tool. In terms of actual use cases, maybe something like rsync'ing a large directory where only a few files have changed? It starts to get pretty contrived though.
the biggest joy is that you get it back in the form of a credit over several years, all the while paying interest and fees on the tax bill you cant initially pay because your "gains" are in a private company's stock that you cant sell! I've yet to get a rational explanation of why the current AMT law is fair. sure for some people it makes sense, but for the exercise of ISOs in a private company, it's basically robbery where they give you a chunk of what they stole back every year, and hopefully a liquidity event comes along sooner rather than later
Per Buy, Borrow, Die, they could take a margin loan using that $1M and use borrowed money (say $100K) to pay the rent. With enough accumulated shares, they wouldn't need to sell the shares in their lifetime. After they've passed away, they would pay off the loan and the stock gets a free step up to the appreciated cost basis.
The reason we have capital gains is to encourage investment. They're not investing $1 for 1m shares to build something better. They're getting $1m worth of something for $1, risk-free.
That gap between strike price and FMV is much more like compensation than it is an investment.