The important thing is that once they have cashed those 500 million, they will buy Bitcoin on the open market during the early European Hours, when liquidity is thin, and they are not going to be shy. They will lift the market in European hours for approximatively 6,500 BTC.
I'm not going to criticize Michael Saylor, so don't flame me, but if he buys bitcoin that way is it in the best interest of MSTR's shareholders? AFAIK he's got a fiduciary responsibility to use Microstrategy's money & resources in the most responsible manner possible, and I'd think that getting a loan for that much money and buying bitcoin at a time when trading volume is relatively low might raise some eyebrows at the very least.
Aside from that, you can't argue with MSTR's stock price right now ($1695 as I write this). Never would have thought it'd go that high, but I've been proven wrong once again.