The reason STRC is arguably a flawed instrument is also the reason it was able to attract $7bn in 3 months

By having a pref that is supposed to trade at $100 and with a "variable" but extremely slow adjusting yield (set by Saylor and not directly by the market forces), Strategy has been able to gather a ton of volume and demand to an instrument that didn't have a clear equilibrium level at $100, but was 'forced' there

The other prefs are much better designed assets because the market sets their yield instantly by repricing them. Saylor was able to get $7bn of 'inorganic' inflows in STRC that he wouldn't have gotten in STRF for example, because the price of STRF would have automatically gotten pushed down way more than STRC and its artificial peg at $100

Now the market has to absorb all of this 'excessive leverage' that has been taken by Strategy, one way or another. It's interesting to notice how incredibly ruthless the market is, Saylor took two stupid decisions in a row (buying $2bn of BTC at the highs with the STRC money and then retiring the converts with the USD reserve), and the reaction has been immediate: $MSTR has dumped -55% in what's been just a bit more than a month.