Ironically if they start selling their shares would suffer more
Meaning their investors would suffer more than people holding Bitcoin.
They have more to loss than hodlers.
When the share rises an investor can choose to sell. That's different from strategy selling Bitcoin.
They won't keep holding forever, will they? At some point, MicroStrategy will eventually sell portions of their Bitcoin, maybe not all at once, but gradually over time. Of course, they won't just sell because they
meedneed to. They're more likely to wait for a new ATH to maximize returns. After all, their stock performance is now heavily tied to Bitcoin's price, so they will carefully time any liquidation to avoid negatively impacting their own shares.