Institutional investors, such as hedge funds and corporations, have different ways of storing and protecting their Bitcoin assets than typical user wallets.
A lot have been discussed under this thread already and I believe your doubt have been cleared. That's one advantage of this forum because whatever you want to know, there are experts here who can put you through. I will not be left out from offering my two cents concerning the topic of discussion. Bitcoin is a risky digital asset which is difficult to trace when lost. Institutional investors are always cautious and careful when it comes to bitcoin security. Due to some fear of attacks, some institutional investors use third-party custodians to help manage and protect their Bitcoin holdings while some institutional investors typically use a combination of cold storage and multi-signature wallets to secure their Bitcoin assets. So I think it depends on the what or which one they consider more secured to them.