And if you listen to Michael Saylor's interview with Binance [1], the store-of-value argument is at the core of his rationalle/narrative (it's a rather long video, but he gives a complete explanation of his motivation in the first 5 minutes, I think).
I believe MicroStrategy's first investment into BTC was really a case of their corporate treasury making a rather bold (desperate?) move to preserve their asset value in the wake of an absolutely gigantic recent expansion of M2 money supply, and a sign of more of the same rolling beyond the horizon.
Basically, they decided it was worth taking all the the risks of BTC (regulatory, operational, technical, market risk) to get away from the certainty of their fiat assets getting essentially debased by the looming inflation.
But this business of levering up to go even longer is a pure balls-to-the-wall bet tho. It's completely nuts, and I love it. The guy obviously believes in his investment thesis, and you have to give him the credit for being the risk taker in the best tradition of The American Dream.
OK, he didn't exactly bet the company on it, but it's still a ballsy business move, if there ever was one.
Let me spell out a clearer downside:
If Bitcoin goes to 0, you're left holding a boring business analytics company that punted off its entire cash balance on a risky bet.
Or another downside: The SEC launches a second investigation into the CEO. After the last settlement the CEO of this company saw his net worth drop $6Bn which is double the market cap of MSTR.