yes, Covid might have extended the trajectory by a year or so, but it did not really cause the interest, by then D&D was already huge. It only helped to sustain the already existing momentum
Right. But I don't think you realize how utterly mind-blowing that is, to "sustain the already existing momentum".
Games have momentum like a pile of bricks. Unless it's obscure (which, among TTRPGs, D&D is by far the least qualified), the sales peak of a new game is heavily front-loaded -- everyone rushes to buy new thing, at which point mostly everyone has new thing, and you generally don't buy durable goods twice. Conventional wisdom is that momentum is
impossible to sustain, which is why D&D traditionally follows a "splat, bloat, reset" lifecycle. (I don't like it, but they basically have to do that to stay solvent.) TSR's cycle was about a decade, and they almost went under twice. WotC picked them up, and since then released either a major revision or a completely new version every 3-6 years -- until 5th Edition.
Whatever sustaining of "already existing momentum" D&D saw over the past decade was staggering and unprecedented in its history, and well beyond what can be chalked up to Hasbro being a savvy company.