Ann: Opthea Completes Placement & Institutional Entitlement Offer, page-38

I suggest you go a study any number of dozens of recent capital raisings on the ASX and you might change your tune. Relatively, to recent raises and given size, it was an excellent take up.

Some 61% of Insto' entitlements taken up? In an accelerated short notice raise? Perhaps do a little background checking on other offers.

I wouldn't quite call it "massive" per @cbcb's comments, but by measure of most other recent similar capital raisings on the ASX it the Insto's take-up impressively beat my expectations.