Why doesn't classical music ever stay intense for more than a minute or so?

Ok, let’s get intense!

Grande Tarantelle for Piano and Orchestra - Louis Moreau Gottschalk

A version with video of the pianist!
And yes, I have the music. It’s eye-wateringly intense to try and play.

Unable to sustain the intensity, you say?

This is a problem with modern listeners confronting classical music. I have a problem with the Firebird Suite. You love the theme and it’s famous. But if you listen to the piece you might miss the part you recognize completely. It’s just the climax. The rest doesn’t sound like it to me, at least until I acclimate to it, if I can.

Fun fact: that ubiquitous Fairlight orchestral stabused in countless 1980s and 90s pop songs was sampled from the “Infernal Dance” movement of the Firebird Suite.