We don't know or we are not interested in new IPs because they are not crafted with high quality (which means putting resources in to it) and they are not promoted heavily like everything mainstream.
There are still big budget new IP being made, such as Starfield. After a few years you can try to compare the sales with The Elder Scrolls 5/6 and see which sell better.
Personally I am more interested in TES6, even if both has similar quality and budget. because I have more emotional attachment to TES lores and the world, Starfield set in a world that I know nothing about.
IMO Budget is one thing that gets our attention but not everything. Emotional attachment plays a big role.
On the other, it is obvious that the entertainment industry is pushing for remakes, prequels and sequels because it's much cheaper than establishing and promoting new IPs.
Even indie new IPs often use old IP to sell their games tbh. I played stardew valley a few years ago because people said it's like harvest moon, and I have emotional attachment to harvest moon. Same can be said for Crystal Project and Cassette Beasts. I got interested in these games because people mentioned FF5 and Pokemon when they talked about these games. And I love FF5 and Pokemon.
Even genre defining indie hit like Vampire Survivors has castlevania reference in it. I have to admit I clicked on it when it showed up because of Castlevania reference lol.
It's definitely true that it is easier to sell an old IP. But I don't think it is pushed by the game dev. It's how consumers behave so game dev only make money off consumer's behaviour and emotional needs.