Bullet Train worth it when already doing a day trip to Mt Fuji?

Hey everyone. I will be going to Japan in March 2026. I am trying to make this trip as budget friendly as possible. I'm a little bit stuck on what to do in this situation and need some guidance.
Is the bullet train from Tokyo to Kyoto worth it, please note I'm already planning to do a day trip to see Mt fuji.
The train tickets are quite expensive and I'm wondering if i should just fly as i believe it will be cheaper to get a ticket between now and then.

Please any advice is welcome, thanks truly a confused solo traveller.