Kevin Drum asks:

Reading Tim Pawlenty's paean to double plus supply-side-ism yesterday made me wonder, once again, why conservatives think we liberals are opposed to it. I mean, if it actually worked, why would we be? It's politically popular, and by their accounts it would generate trillions of dollars in extra revenue that we could use to finance our beloved lefty social programs. What's not to like?
The only answer I can come up with is that conservatives are now completely invested in their theory that we liberals loathe rich people so much that we don't care. We all want to screw the wealthy so badly that we're willing to forego the elections we'd win and the mountains of revenue we'd gain if we lowered their taxes. We hate them that much.
Or is there some other wacky theory that's popular in conservative circles but that I'm unaware of?

No, that's exactly it. The early supply-siders, like Jude Wanniski and Jack Kemp, were sure they could convert liberals to their theory once they had learned the Good News. They actually viewed liberals as their most promising potential converts, precisely because they believed they had unlocked the key to higher revenue at no cost. They genuinely, tirelessly evangelized for years.

Eventually, pretty much all of them gave up on this hope. Now they almost all believe liberals hate the rich so much they're willing to sacrifice economic growth and revenue in order to punish them.