Many people who ride it have one of various train passes that reduce the cost, or have a plan with work that covers it. I usually use a JR pass, it's pretty expensive without it.
Unfortunately the JR pass literally doubled in price in Oct 2023, it's now 50,000 yen for 7 days and makes no sense unless you're planning to speedrun the length of Japan and back.
Yep, it is not worth it anymore. I got mine for my trip at the end of the year on literally the last day it was on sale :). End of an era.
Note that 50,000 yen is $335. So that’s a ceiling on how much you’ll spend for 7 days of Shinkansen travel.