It’s plastic brick produced by a machine. It probably costs Lego $1.25 to manufacture. The main expense is paying the designers who come up with these things.
If I had kids, I’d probably buy used sets, or just the “bucket of bricks”, or wait until something went on sale. When I was a kid I got a suitcase of used legos at a garage sale one time and was in heaven. I don’t think kids really care about “sets” as much until they reach the Technics age and are using them to learn about how gear movements work. Little kids like to just mix and match to make stuff from their imagination.
As an adult, I visited a Lego store recently and saw some neat stuff. But I’m not paying for these extravagant sets that cost a small fortune. I might consider buying something used if wasn’t a “collectible” that increased in value.