A few days back he tweeted that he bought using the Cash app. So most likely he is maxing out his credit card buying bitcoin. He seems addicted. And its great and all. However if bitcoin keeps dipping into his average, he might get in trouble and might get pressure to sell some of his holding. He has like 100K BTC which won't be easy to unload, especially in a neutral or bear market. Hence you need to becareful.
So far, Saylor remains the only large holder who constantly buys bitcoin, stimulating its growth, although the trend has changed and, fundamentally, now bitcoin is more determined to continue its decline. Saylor recently tweeted that he does not sell bitcoin, apparently letting the community know that he is still the same holder and is not going to change anything. If MicroStrategy starts to get rid of Bitcoin, then the market can go deep down. I think the company will have enough resources to wait out this correction without selling its assets.