And the company can get it wrong, as it did many times. No, I am not expecting soccer moms stashing away unopened boxes.
First, what matters for a success of a major non-necessity product is mind share and public perception. In the recent years LEGO has been perceived as a premium product, that has a good value even being used. People don't need to have the intention to sell it, it is enough if they know that they can sell it if they want to. That is the important bit here, which changes the nature of the purchase. Instead of burning money, you are still at your money when purchasing. All the articles and social media feedback ensured that people knew this. This has a huge influence on purchasing decisions, even if just subconsciously.
Second, LEGO overshooting and mismanaging its product pipeline is mostly a separate issue. They missed the focus and fail to notice some trends. They were too late with catering to the adult market, and were releasing too much dinky crap (Nexo, SH Girls, Chima, etc.). These fail to pass the 'parent test', where they are approved for purchase. In many families purchase of a large LEGO set is a significant expense and gets considered carefully which one to buy. The enduring popularity of classic and ordinary themes such as Creator, City, Friends and a few SW sets are clearly explained by the parent influence on purchasing decisions.
Third, nobody realizes that people are getting tired of Star Wars and Super Heroes by now. An endless wave of movies, accompanied by sets of questionable design quality. The SW and Marvel brands are squeezed dry by Disney, there is just too many movies and other products coming. The people cannot keep up anymore by the new heroes and vehicles, and are losing interest. Less is more, but the managers have to show the profits now for the fat bonus. Disney is not killing these by quality, but by quantity, and the signs are alarming already. LEGO is caught up in this disease big time, and the amount of sets they cannot get rid of even with a 50% discount is shocking. LEGO should at least halve the amount of sets in these themes and put more effort into the design.
Fourth, the market research they do is a glorious mess, the whole department should be fired. Consecutively misses the mark in terms of which sets should be advertised and produced in large quantity. The literal gold mines are left unexploited. Millions were spent on marketing Nexo, however it is the sets like the Saturn V that already should have TV ads and mass production to capitalize on the public reception. That could be toy of the year this Christmas, but the company has grown too incompetent to catch on. And from which dark hole did they get the stupid idea that anybody would want SH Girls? Seriously.