Star Wars (1977) has existed for 40 years and generations have been raised on it. It's considered a movie classic. The film is undeniably iconic around the world. Empire Strikes Back is praised as one of the greatest sequels all time. Return of the Jedi is good.
The Force Awakens was divisive, although I love it, and has only been out two years. The Last Jedi still isn't even out for another few hours at the time of posting this. We have no idea what Episode IX will even be called yet.
While yes, The Force Awakens did gangbusters, and The Last Jedi will probably do the same, the prequels did pretty well financially but they did not hold up at all. Imagine if Disney had started construction on a land themed to the prequel trilogy in 2000 and opened it in 2004? It'd have been a huge mistake. While I don't think the new trilogy will be hated like the prequels were, it feels like they're putting the cart in front of the horse a little bit. I'm all for risks, but unless the next two movies in the trilogy are praised higher by the general public than the Original Trilogy, then they're just playing it stupid imo.