Because some managers and Funds are obligated to own Bonds and Fixed income products by their investors.  Like 10% of their portfolio for example must be allocated to Bonds.  That in recent history has been just burning money but they are obligated to own it . Now MSTR offers them something (convertible bond offering) in that space that actually performs and managers will buy up every offering that they possible can. 

 I think we will see open defiance of such rules in the next 5 years. Then we shall learn what the enforcement mechanisms are. 

 Unless the owners of those funds (pensioners. employees, retirees) actually go in and sell their retirement funds and move it themselves (never going to happen).  That money will never be ported into the bitcoin universe, it will be permanently stuck in Tradfi land.  The wealth is fake there.  It's fake numbers.  Fake money.